Texas Instruments Calculator TI 80 User Manual

TI-80  
GRAPHING CALCULATOR  
GUIDEBOOK  
TI-GRAPH LINK, Calculator-Based Laboratory, CBL, CBL 2, Calculator-Based Ranger, CBR,  
Constant Memory, Automatic Power Down, APD, and EOS are trademarks of Texas  
Instruments Incorporated.  
Windows is a registered trademark of Microsoft Corporation.  
Macintosh is a registered trademark of Apple Computer, Inc.  
© 1995–1997, 2001 by Texas Instruments Incorporated.  
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Table of Contents  
gives a quick overview of its features. The first chapter gives general  
instructions on operating the TI.80. Other chapters describe its interactive  
features. The applications in Chapter 11 show how to use these features  
together.  
Using this Guidebook Effectively....................  
Glossary .........................................  
viii  
xii  
Getting Started:  
Do This First!  
TI-80 Keyboard ...................................  
First Steps .......................................  
TI-80 Menus......................................  
Entering a Calculation: Compound Interest...........  
Continuing a Calculation ...........................  
Defining a Function: Box with Lid ...................  
Defining a Table of Values..........................  
Zooming In on the Table ...........................  
Changing the Viewing Window......................  
Displaying and Tracing the Graph ...................  
Zooming In on the Graph...........................  
Other TI-80 Features ..............................  
2
3
4
5
6
7
8
9
11  
12  
13  
14  
Chapter 1:  
Operating the  
TI-80  
Turning the TI-80 On and Off .......................  
Setting the Display Contrast ........................  
The Display ......................................  
Entering Expressions and Instructions...............  
The Edit Keys ....................................  
Setting Modes ....................................  
1-2  
1-3  
1-4  
1-6  
1-8  
1-9  
TI-80 Modes...................................... 1-10  
Variable Names ................................... 1-12  
Storing and Recalling Variable Values................ 1-13  
Last Entry........................................ 1-14  
Last Answer...................................... 1-16  
TI-80 Menus...................................... 1-17  
The VARS and Y-VARS Menus...................... 1-19  
EOS (Equation Operating System) .................. 1-20  
Error Conditions ................................. 1-22  
Introduction iii  
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Chapter 2:  
Getting Started: Lottery Chances ....................  
Math, Angle, and Using the TI-80 Functions..........................  
2-2  
2-3  
2-4  
2-7  
Test Operations  
Keyboard Math Operations .........................  
MATH MATH Operations ...........................  
MATH NUM (Number) Operations ................... 2-10  
MATH PRB (Probability) Operations................. 2-12  
ANGLE Operations ................................ 2-14  
TEST (Relational) Operations....................... 2-16  
Chapter 3:  
Fractions  
Getting Started: Working with Fractions .............  
Setting Modes for Fraction Results ..................  
Entering and Using Fractions in Calculations .........  
The FRACTION Menu..............................  
3-2  
3-4  
3-6  
3-8  
Chapter 4:  
Function  
Graphing  
Getting Started: Graphing a Circle...................  
Defining a Graph..................................  
Setting Graph Modes ..............................  
Defining Functions in the Y= List....................  
Selecting Functions ...............................  
Defining the Viewing Window ......................  
4-2  
4-3  
4-4  
4-5  
4-7  
4-8  
4-9  
Displaying a Graph ................................ 4-11  
Exploring a Graph with the Free-Moving Cursor ...... 4-12  
Exploring a Graph with TRACE ..................... 4-13  
Exploring a Graph with ZOOM...................... 4-15  
Setting the Zoom Factors .......................... 4-18  
Chapter 5:  
Parametric  
Graphing  
Getting Started: Path of a Ball ......................  
Defining and Displaying a Parametric Graph..........  
Exploring a Parametric Graph ......................  
5-2  
5-3  
5-6  
iv Introduction  
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Chapter 6:  
Tables  
Getting Started: Roots of a Function.................  
Defining the Independent Variable ..................  
Defining the Dependent Variable ....................  
Displaying the Table...............................  
6-2  
6-3  
6-4  
6-5  
Chapter 7:  
Getting Started: Shading a Graph....................  
7-2  
7-3  
7-4  
7-5  
7-6  
7-7  
Draw Operations DRAW DRAW Menu ...............................  
Drawing Lines ....................................  
Drawing Horizontal and Vertical Lines ...............  
Shading Areas on a Graph ..........................  
Drawing Points ................................... 7-10  
Clearing a Drawing................................ 7-12  
Chapter 8:  
Lists  
Getting Started: Generating a Sequence ..............  
About Lists.......................................  
LIST OPS Operations ..............................  
LIST MATH Operations ............................  
8-2  
8-3  
8-6  
8-9  
Chapter 9:  
Statistics  
Getting Started: Building Height and City Size.........  
Setting Up a Statistical Analysis.....................  
The STAT List Editor ..............................  
9-2  
9-8  
9-9  
Viewing, Entering, and Editing Lists ................. 9-10  
Sorting and Clearing Lists .......................... 9-13  
Statistical Analysis ................................ 9-14  
Types of Statistical Analysis ........................ 9-15  
Statistical Variables ............................... 9-17  
Statistical Plotting ................................ 9-18  
Statistical Analysis in a Program .................... 9-22  
Statistical Plotting in a Program..................... 9-23  
Introduction v  
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Chapter 10:  
Programming  
Getting Started: Rolling a Die ....................... 10-2  
About TI-80 Programs ............................. 10-4  
Creating and Executing Programs ................... 10-5  
Editing Programs ................................. 10-6  
PRGM CTL (Control) Instructions ................... 10-7  
PRGM I/O (Input/Output) Instructions ............... 10-11  
Calling Other Programs ............................ 10-14  
Chapter 11:  
Applications  
Probability Experiments: Coins, Dice, and Spinners ... 11-2  
The Unit Circle and Trigonometric Curves............ 11-3  
Program: Newton’s Numerical Solve Routine ......... 11-4  
Program: Numerical Integration..................... 11-6  
Program: Window Variables Store and Recall ......... 11-8  
Graphing the Inverse of a Function .................. 11-10  
Graphing a Piecewise Function ..................... 11-12  
Graphing Inequalities .............................. 11-14  
Graphing a Polar Equation ......................... 11-15  
Program: Guess the Coefficients .................... 11-16  
Chapter 12:  
Memory  
Management  
Checking Available Memory ........................ 12-2  
Deleting Items from Memory ....................... 12-3  
Resetting the TI-80 ................................ 12-4  
vi Introduction  
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Appendix A:  
Tables and  
Reference  
Table of TI-80 Functions and Instructions ............  
Menu Map........................................ A-20  
TI-80 Variables ................................... A-26  
A-2  
Information  
Appendix B:  
Service and  
Warranty  
Battery Information ...............................  
Accuracy Information .............................  
In Case of Difficulty ............................... B-10  
Service and Support Information ................... B-14  
Warranty Information.............................. B-15  
B-2  
B-8  
Information  
Index  
Introduction vii  
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Using this Guidebook Effectively  
The structure of the TI-80 guidebook and the design of its pages can help you  
find the information you need quickly. Consistent presentation techniques are  
used throughout to make the guidebook easy to use.  
Structure of the  
Guidebook  
The guidebook is designed to teach you how to use the  
calculator.  
¦
Getting Started is a fast-paced, keystroke-by-keystroke  
introduction.  
¦
Chapter 1 describes general operation and lays the  
foundation for Chapters 2 through 10, which describe  
specific functional areas of the TI-80. Most chapters begin  
with a brief Getting Started introduction.  
¦
¦
Chapter 11 contains application examples that incorporate  
features from different functional areas of the calculator.  
These examples can help you see how different functional  
areas work together to accomplish meaningful tasks.  
Chapter 12 describes memory management.  
Page-Design  
Conventions  
When possible, units of information are presented on a single  
page or on two facing pages. Several page-design elements  
help you find information quickly.  
¦
Page headings—The descriptive heading at the top of the  
page or two-page unit identifies the subject of the unit.  
¦
General text—Just below the page heading, a short  
section of bold text provides general information about  
the subject covered in the unit.  
¦
Left-column subheadings—Each subheading identifies a  
specific topic or task related to the page or unit subject.  
viii Introduction  
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¦
¦
Specific text—The text to the right of a subheading  
presents detailed information about that specific topic or  
task. The information may be presented as paragraphs,  
numbered procedures, bulleted lists, or illustrations.  
Page “footers”—The bottom of each page shows the  
chapter name, chapter number, and page number.  
Information-  
Mapping  
Several conventions are used to present information concisely  
and in an easily referenced format.  
Conventions  
¦
Numbered procedures—A procedure is a sequence of  
steps that performs a task. In this guidebook, each step is  
numbered in the order in which it is performed. No other  
text in the guidebook is numbered; therefore, when you  
see numbered text, you know you should perform the  
steps sequentially.  
¦
Lists with bullets—If several items have equal  
importance, or if you may choose one of several  
alternative actions, this guidebook precedes each item  
with a “bullet” (¦) to highlight it—like this list.  
¦
¦
Tables and charts—Sets of related information are  
presented in tables or charts for quick reference.  
Keystroke examples—The Getting Started examples  
provide keystroke-by-keystroke instructions, as do the  
numerous short examples and several detailed examples  
that are identified with a .  
Introduction ix  
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Reference Aids  
Several techniques have been used to help you look up  
specific information when you need it. These include:  
¦
A chapter table of contents on the first page of each  
chapter, as well as the full table of contents at the front of  
the guidebook.  
¦
¦
A glossary at the end of this section, defining important  
terms used throughout the guidebook.  
An alphabetical table of functions and instructions in  
Appendix A, showing their correct formats, how to access  
them, and page references for more information.  
¦
¦
Information about system variables in Appendix A.  
A table of error messages in Appendix B, showing the  
messages and their meanings and giving problem-handling  
information.  
¦
An alphabetical index at the back of the guidebook, listing  
tasks and topics you may need to look up.  
x Introduction  
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Glossary  
This glossary provides definitions for important terms that are used throughout  
this guidebook.  
Argument  
Command  
An argument is an input upon which the value of a function  
depends.  
A command is any entry submitted to the calculator using  
¸. There are two types of TI-80 commands: instructions  
and expressions.  
Expression  
Function  
An expression is a complete sequence of numbers, variables,  
functions, and their arguments that can be evaluated to a  
single answer. An expression returns the evaluated result to  
ANS.  
A function, which may have arguments, returns a value and  
can be used in an expression.  
A function is also the expression entered in the Y= editor used  
in graphing.  
Home Screen  
Instruction  
List  
The Home screen is the primary screen of the TI-80, where  
expressions can be entered and evaluated and instructions  
can be entered and executed.  
An instruction, which may have arguments, initiates an action.  
Instructions are not valid in expressions. An instruction does  
not return a value to ANS.  
A list is a set of values that the TI-80 can use for activities  
such as evaluating a function at multiple values and entering  
statistical data.  
Menu Items  
Menu items are shown on full-screen menus.  
Introduction xi  
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Pixel  
A pixel (picture element) is a square dot on the TI-80 display.  
The TI-80 display is 64 pixels wide and 48 pixels high.  
Real Number  
Value  
On the TI-80, real numbers are individual decimal or fraction  
values.  
A value is a single decimal or fraction number or a list of  
decimals or fractions.  
Variable  
A variable is the name given to a location in memory in which  
a value, an expression, a list, or another named item is stored.  
xii Introduction  
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Getting Started: Do This First!  
Getting Started contains two keystroke-by-keystroke examples an interest rate  
problem and a volume problem which introduce you to some principal  
operating and graphing features of the TI.80. You will learn to use the TI.80 more  
quickly by completing both of these examples first.  
Contents  
TI-80 Keyboard ...................................  
First Steps .......................................  
TI-80 Menus......................................  
Entering a Calculation: Compound Interest...........  
Continuing a Calculation ...........................  
Defining a Function: Box with Lid ...................  
Defining a Table of Values..........................  
Zooming In on the Table ...........................  
Changing the Viewing Window......................  
Displaying and Tracing the Graph ...................  
Zooming In on the Graph...........................  
Other TI-80 Features ..............................  
2
3
4
5
6
7
8
9
11  
12  
13  
14  
Getting Started 1  
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TI-80 Keyboard  
The keys on the TI.80 are grouped by color and physical layout to allow easy  
location of the key you need. The keys are divided into zones: graphing keys,  
editing keys, advanced function keys, and scientific calculator keys.  
The Zones of the  
Keyboard  
Graphing  
&
&
Editing  
Advanced  
Functions  
&
Scientific  
Calculator  
&
These keys are most frequently used to access the interactive  
graphing features of the TI-80.  
Graphing Keys  
Editing Keys  
These keys are most frequently used for editing expressions  
and values.  
Advanced  
These keys are most frequently used to access the advanced  
Function Keys  
functions of the TI-80.  
Scientific  
Calculator Keys  
These keys are most frequently used to access the capabilities  
of a standard scientific calculator.  
2 Getting Started  
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First Steps  
Before beginning the two sample problems, follow the steps on this page to  
reset the TI-80 to its factory settings. (Resetting the TI-80 erases all previously  
entered data.) This ensures that following the keystrokes in this section  
produces the same actions.  
x
1. Press ´ to turn the calculator on.  
If the screen is very dark or blank, adjust the display  
E
contrast. Press and release 2, and then press and  
hold 8 (to make the display lighter) or press and  
hold 7 (to make the display darker). You can press  
M to clear the display.  
2. Press and release 2, and then press µ. (Pressing  
2 gives you access to the 2nd operations, which are  
printed at the upper left of the keys. MEM is the  
2nd operation of the µ key.)  
The MEMORY menu is displayed.  
3. Press 3 to select RESET... from the MEMORY menu.  
The MEMORY RESET menu is displayed.  
4. Press 2 to select RESET from the MEMORY RESET  
menu. The calculator is reset, and the  
MEM CLEARED message is displayed.  
Getting Started 3  
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TI-80 Menus  
To leave the keyboard uncluttered, the TI.80 uses full-screen menus to display  
many additional operations. The use of specific menus is described in the  
appropriate chapters.  
Displaying a Menu  
When you press a key that displays a menu, such as  
I, that menu screen temporarily replaces the screen  
where you are working.  
After you make a selection from a menu, you usually are  
returned to the screen where you were.  
Moving from One Menu to Another  
A menu key may display more than one menu name. The  
names appear on the top line. The name of current menu  
is highlighted, and the items in that menu are displayed.  
Use 9 or 6 to display a different menu.  
Selecting an Item from a Menu  
The number of the current item is highlighted. If there are  
more than seven items on the menu, a $ appears on the  
last line in place of the : (colon).  
To select from a menu, you can either:  
¦
Use 8 and 7 to move the cursor to the item, and  
then press ¸.  
¦
Press the number of the item.  
Note: The tenth item in a menu is number 0. If there are  
more than 10 items, they are numbered A, B, C, etc. To  
select one of these items, press ? and then the  
letter.  
Leaving without Making a Selection  
To leave a menu without making a selection:  
¦
¦
Press 2 . to return to the Home screen.  
Press M to return to the screen where you  
were.  
¦
Press the key for another screen or menu.  
4 Getting Started  
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Entering a Calculation: Compound Interest  
The TI.80 displays up to 8 16-characters lines so that you see an expression and  
its solution together. You can store values to variables, enter multiple  
instructions on one line, and recall previous entries.  
Using trial and error, determine when an amount invested at 6% annual  
compounded interest will double in value.  
1. For the first guess, compute the amount available at  
the end of 10 years. Enter the expression just as you  
would write it. (Use 1000 for the amount.)  
Press 1000 p 1.06 Z 10.  
2. Press ¸ to evaluate the expression.  
The answer is shown on the right side of the display.  
The cursor is positioned on the next line, ready for  
you to enter the next expression.  
3. The next guess should be greater than 10 years. Make  
the next guess 12 years. To calculate the amount after  
12 years, press 1000 p 1.06 Z 12, followed by ¸.  
Getting Started 5  
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Continuing a Calculation  
To save keystrokes, you can use the Last Entry feature to recall the last  
expression entered and then edit it for a new calculation. In addition, the next  
expression can be continued from the previous result.  
1. The next guess should be less than, but close to, 12  
years. Compute the amount available at the end of  
11.9 years, using the Last Entry feature. Press 2,  
followed by ² (the second function of ¸).  
The last calculated expression is shown on the next  
line of the display. The cursor is positioned at the end  
of the expression.  
2. You can edit the expression. Press 6 to move the  
cursor over the 2. Then type 1.9 to change 12 to 11.9.  
Press ¸ to evaluate the expression.  
Note: This process can be continued to obtain a  
solution with the desired accuracy.  
3. You can continue a calculation using the result of the  
last calculation. For example, if the final amount  
determined above is to be divided among seven  
people, how much would each person get?  
To divide the last calculation by seven, press e 7,  
followed by ¸.  
As soon as you press e, ANSà is displayed at the  
beginning of the new expression. ANS is a variable  
that contains the last calculated result. In this case,  
ANS contains 2000.505716.  
6 Getting Started  
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Defining a Function: Box with Lid  
Take an 8½"×11" sheet of paper and cut X by X squares from two corners and X  
by (X+B) rectangles from the other two corners. Now fold the paper into a box  
with lid. What X would give the maximum volume V of a box made in this way?  
Use tables and graphs to determine the solution.  
Begin by defining a function that describes the  
X
volume of the box.  
W
A
X
From the diagram:  
2X + A = W  
2X + 2B = L  
V = A B X  
B
X
B
Substituting: V = (W – 2X) (L à 2 – X) X  
L
If necessary, press z † Í to change the  
MODE to FLOAT. Then press y . to  
return to the Home screen and clear it.  
1. Press 8.5 ¿ ƒ W Í to store the width of  
the paper.  
Press 11 ¿ ƒ L Í to store the length of  
the paper.  
2. You define functions for tables and graphs on the Y=  
edit screen.  
Press o to access this screen.  
3. Enter the function for volume as Y1. Press £ ƒ  
W ¹ 2 @ ¤ £ ƒ L ¥ 2 ¹ @ ¤ @ Í  
to define function Y1 in terms of X. (@ lets you  
enter X quickly without pressing ƒ.)  
The = sign is highlighted to show that Y1 is selected.  
Getting Started 7  
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Defining a Table of Values  
The table feature of the TI.80 provides numeric information about a function.  
Use a table of values from the previously defined function to estimate an answer  
to the problem.  
1. Press y # (above p) to display the  
TABLE SETUP screen.  
2. Press Í to accept TBLMIN=0.  
3. Press .5 Í to define the table increment @TBL=.5.  
4. Press y & (above s) to display the table.  
Note that the maximum value is around 1.5, between  
1 and 2.  
5. Press and hold to scroll the table until the sign  
change appears. Note that the maximum length of X  
for this problem occurs where the sign of Y1  
(volume) becomes negative.  
6. Press y #. Note that TBLMIN has changed to  
reflect the first line of the table you last displayed.  
8 Getting Started  
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Zooming In on the Table  
You can adjust the way a table is displayed to get more detailed information  
about any defined function. By varying the value of @TBL, you can “zoom in” on  
the table.  
1. Adjust the table setup to get a more accurate  
estimate of the maximum size of the cutout. Press 1  
Í to set TBLMIN. Press .1 to set @Tbl.  
2. Press y &.  
3. Use and } to scroll the table. Note that the  
maximum value displayed is 33.072, which occurs at  
X=1.6. The maximum occurs at 1.5<X<1.7.  
Getting Started 9  
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4. Press y #. Press 1.5 Í to set TBLMIN.  
Press .01 Í to set @TBL.  
5. Press y & and use and } to scroll the table.  
Two “equal” maximum values are shown, 33.074 at  
X=1.58 and X=1.59.  
6. Press or } to move the cursor to 1.58. Press ~ to  
move the cursor into the Y1 column. The bottom line  
of the display shows the value of Y1 at 1.58 in full  
precision, 33.073824.  
7. Press to display the “other” maximum. The value  
of Y1 at 1.59 in full precision is 33.073908. This  
would be the maximum volume of the box if you  
could cut your piece of paper at .01-inch increments.  
10 Getting Started  
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Changing the Viewing Window  
The viewing window defines the portion of the coordinate plane that appears in  
the display. The values of the Window variables determine the size of the  
viewing window. You can view and change these values.  
1. Press p to display the Window variables edit  
screen. You can view and edit the values of the  
Window variables here.  
The standard Window variables define the viewing  
YMAX  
window as shown. XMIN, XMAX, YMIN, and YMAX  
define the boundaries of the display. XSCL and YSCL  
XSCL  
XMIN  
define the distance between tick marks on the X and  
XMAX  
Y axes.  
YSCL  
YMIN  
2. Press 0 Í to define XMIN.  
3. You can enter expressions to define values in the  
window editor. Press  
8.5 ¥ 2.  
4. Press Í. The expression is evaluated, and 4.25 is  
stored in XMAX. Press Í to accept XSCL as 1.  
5. Press 0 Í 40 Í 10 Í to define the Y  
Window variables.  
Getting Started 11  
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Displaying and Tracing the Graph  
Now that you have defined the function to be graphed and the window in which  
to graph it, you can display and explore the graph. You can trace along a  
function with TRACE.  
1. Press s to graph the selected function in the  
viewing window.  
The graph of Y1=(W–2X)(Là2–X)X is shown in the  
display.  
2. Press ~ once to display the free-moving cursor just  
to the right of the center of the screen. The bottom  
line of the display shows the X- and Y-coordinate  
values for the position of the graph cursor.  
3. Use |, ~, }, and to position the free-moving  
cursor at the apparent maximum of the function.  
As you move the cursor, X- and Y-coordinate values  
are updated continually to reflect the cursor position.  
4. Press r. The Trace cursor appears on the Y1  
function. 1 in the upper right corner of the display  
shows that the cursor is on Y1. As you press | and  
~, you trace along Y1, one X dot at a time, evaluating  
Y1 at each X.  
5. Press | and ~ until you are on the maximum Y  
value. This is the maximum of Y1(X) for the X pixels.  
(There may be a maximum value “in between”  
pixels.)  
12 Getting Started  
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Zooming In on the Graph  
You can magnify the viewing window around a specific location using the Zoom  
instructions to help identify maximums, minimums, roots, and intersections of  
functions.  
1. Press q to display the ZOOM menu.  
This menu is typical of TI-80 menus. To select an  
item, you may either press the number to the left of  
the item, or you may press until the item number is  
highlighted and then press Í.  
2. To ZOOM IN, press 2. The graph is displayed again.  
The cursor has changed to indicate that you are using  
a Zoom instruction.  
3. Use |, }, ~, and to position the cursor near the  
maximum value on the function, and press Í.  
The new viewing window is displayed. It has been  
adjusted in both the X and Y directions by factors of  
4, the values for Zoom factors.  
4. Press p to display the new window variable  
values.  
Getting Started 13  
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Other TI.80 Features  
Getting Started has introduced you to basic calculator operation and the table  
and function graphing features of the TI-80. The remainder of this Guidebook  
describes these features in more detail and also covers other capabilities of the  
TI-80.  
Fractions  
You can enter fractions directly from the keyboard and  
perform calculations with fractions. You can convert between  
fractions and their decimal equivalents. In MANSIMP mode,  
you can simplify fractions step-by-step. The TI-80 tells you  
when a fraction can be simplified and shows the common  
factor after simplification (Chapter 3).  
Graphing  
You can store, graph, and analyze up to four functions  
(Chapter 4) and up to three parametric functions (Chapter 5).  
You can use Draw operations to annotate graphs (Chapter 7).  
Tables  
Lists  
You can create function evaluation tables to analyze multiple  
functions simultaneously (Chapter 6).  
You can enter and save up to six lists for use in statistical  
analysis. You also can use lists to evaluate expressions at  
multiple values simultaneously (Chapter 8).  
Statistics  
You can perform one-variable and two-variable list-based  
statistical analysis, including regression analysis, and plot the  
data as histograms, points, x-y lines, or box-and-whisker plots.  
You can define and save three statistical plot definitions  
(Chapter 9).  
Programming  
You can enter and save programs that include extensive  
control and input/output instructions (Chapter 10)  
14 Getting Started  
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Chapter 1: Operating the TI-80  
This chapter describes the TI.80 and provides general information about its  
operation.  
Chapter  
Contents  
Turning the TI.80 On and Off .......................  
Setting the Display Contrast ........................  
The Display ......................................  
Entering Expressions and Instructions...............  
The Edit Keys ....................................  
Setting Modes ....................................  
1-2  
1-3  
1-4  
1-6  
1-8  
1-9  
TI.80 Modes...................................... 1-10  
Variable Names ................................... 1-12  
Storing and Recalling Variable Values................ 1-13  
Last Entry........................................ 1-14  
Last Answer...................................... 1-16  
TI.80 Menus...................................... 1-17  
The VARS and Y.VARS Menus...................... 1-19  
EOS (Equation Operating System) .................. 1-20  
Error Conditions.................................. 1-22  
Operating the TI-80 1-1  
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Turning the TI-80 On and Off  
To turn the TI.80 on, press the ´ key. To turn it off, press and release y, and  
then press ®. After about five minutes without any activity, the APD™  
(Automatic Power Down™) feature turns the TI.80 off automatically.  
Turning the  
Press ´ to turn the TI-80 on.  
Calculator On  
¦
If you pressed y ® to turn the calculator off, the  
display shows the Home screen as it was when you last  
used it, and errors are cleared.  
¦
If APD turned the calculator off, the display returns to the  
same screen or editor in which you left it. See “APD  
(Automatic Power Down)” below.  
Turning the  
Press and release 2, and then press ® to turn the TI-80  
Calculator Off  
off.  
¦
¦
Any error condition is cleared.  
All settings and memory contents are retained by the  
Constant Memoryé feature.  
APD™  
(Automatic  
Power Down™)  
To prolong the life of the batteries, APD turns the TI-80 off  
automatically after several minutes without any activity. When  
you press ´, the calculator shows the same screen or editor  
in which you left it.  
¦
If an error message was displayed when APD turned the  
TI-80 off, the error is cleared, and the display returns to a  
blank line on the Home screen.  
¦
If a menu was displayed, the display returns to the screen  
or editor from which you called the menu.  
All settings and memory contents are retained by the Constant  
Memory feature.  
Note: APD does not occur if a calculation or program is in  
progress, unless the program is paused.  
Batteries  
The TI-80 uses two CR2032 lithium batteries. To replace the  
batteries without losing any information stored in memory,  
follow the directions in Appendix B.  
1-2 Operating the TI-80  
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Setting the Display Contrast  
The brightness and contrast of the display depend on room lighting, battery  
freshness, viewing angle, and the adjustment of the display contrast. The  
contrast setting is retained in memory when the TI.80 is turned off.  
Adjusting the  
You can adjust the display contrast to suit your viewing angle  
Display Contrast and lighting conditions. As you adjust the contrast setting, the  
display becomes lighter or darker. A highlighted number in the  
upper right corner changes to indicate the current contrast  
setting; 0 is the lightest, and 9 is the darkest.  
To adjust the display contrast:  
1. Press and release the 2 key.  
2. Use one of two keys:  
¦
To increase the contrast (darken the screen), press and  
hold 7.  
¦
To decrease the contrast (lighten the screen), press and  
hold 8.  
Note: The display may become completely blank if you adjust  
the contrast setting too low. If this happens, press and release  
y, and then press and hold 7 until the display reappears.  
When to Replace As you use the TI-80, the battery voltage will gradually drop,  
Batteries  
and the display will dim. You can adjust the contrast to darken  
the display when this happens. If the display is dim and  
adjusting the contrast to level 9 does not make it dark enough,  
you should replace the batteries. Refer to Appendix B for  
instructions on how to change the batteries.  
Note: After you change batteries, the display contrast may  
appear very dark. Press and release y, and then press and  
hold 8 to lighten the display.  
Operating the TI-80 1-3  
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The Display  
The TI.80 displays both text and graphs. Graphs are described in Chapters 4 and 5.  
Home Screen  
The primary screen of the TI-80 is the Home screen. You enter  
instructions to be executed, expressions to be evaluated, and  
see the results on the Home screen.  
Displaying  
Entries and  
Answers  
When text is displayed, the TI-80 screen can show a maximum  
of eight lines with 16 characters each.  
¦
If all lines of the display are filled, text “scrolls” off the top  
of the display.  
¦
If an expression on the Home screen, the Y= editor  
(Chapter 4), or the program editor (Chapter 10) is longer  
than one line, it wraps to the beginning of the next line.  
¦
On numeric editors such as the Window screen  
(Chapter 4), an expression scrolls to the left and right.  
When an entry is executed on the Home screen, the answer is  
displayed on the right side of the next line.  
Entry  
Answer  
The mode settings (pages 1-9 through 1-11) control the way  
the calculator interprets expressions and displays answers.  
If an answer is too long to display in its entirety, you can press  
9 and 6 to scroll the answer so that you can view all of it. In  
the second example below, the open brace without a  
corresponding close brace indicates that the list is too long to  
be displayed in its entirety.  
Entry  
Answer  
Answer  
Answer (scrolled)  
Returning to the  
Home Screen  
To return to the Home screen from any other screen, press  
y ..  
1-4 Operating the TI-80  
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Display Cursors  
In most cases, the appearance of the cursor indicates what  
will happen when you press the next key.  
Cursor  
Appearance  
Meaning  
Entry  
Blinking 0  
The next keystroke is  
entered at the cursor; it  
types over any character.  
INS (insert)  
2nd  
Blinking _  
Blinking Ž  
Blinking   
The next keystroke is  
inserted at the cursor.  
The next keystroke is a 2nd  
operation.  
ALPHA  
The next keystroke is an  
alphabetic character.  
memory “full” Checkerboard You have entered the  
rectangle  
maximum number of  
characters in a name, or  
memory is full.  
Graphs and the screens for viewing and editing tables and lists  
have different cursors, which are described in the appropriate  
chapters.  
Busy Indicator  
When the TI-80 is calculating or graphing, a vertical line  
shows in the upper right of the display as a busy indicator.  
During a pause in a program, the busy indicator is a dotted  
line.  
Operating the TI-80 1-5  
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Entering Expressions and Instructions  
In most places where a value is required, you can use an expression to enter the  
value. You can enter instructions, which initiate an action, on the Home screen  
or in the program editor (Chapter 10).  
Expressions  
An expression is a complete sequence of numbers, variables,  
functions, and their arguments that evaluate to a single  
answer. For example, prñ is an expression. On the TI-80, you  
enter an expression in the same order as you would write it.  
You can create expressions on the Home screen to calculate  
an answer. In most places where a value is required, you can  
use an expression to enter the value.  
Entering an  
Expression  
To create an expression, you enter numbers, variables, and  
functions from the keyboard and menus. An expression is  
completed when you press ¸, regardless of the cursor  
location. The entire expression is evaluated according to  
Equation Operating System (EOSTM) rules, and then the  
answer is displayed.  
Note: EOS rules determine the order in which operations are  
completed (page 1-20).  
Most TI-80 functions and operations are symbols with several  
characters in them. You must enter the symbol from the  
keyboard or menu. You cannot spell it out. For example, to  
calculate the log of 45, you must press l 4 5. You cannot  
type in the letters L O G. (If you type LOG, the TI-80 interprets  
the entry as implied multiplication of the variables L, O, and G.)  
Calculate 3.76 ÷ (-7.9 + 5) + 2 log45.  

3.76 e c · 7.9 «  
y ] 5 d « 2 l 45  
¸
Multiple Entries  
on a Line  
To enter more than one expression or instruction on a line,  
separate them with a colon (:). They are all stored together in  
Last Entry (page 1-15).  
1-6 Operating the TI-80  
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Entering a  
Number in  
Scientific  
Notation  
To enter a number in scientific notation:  
1. Type the part of the number that precedes the exponent.  
This value can be an expression.  
2. Press 2 ^. í is displayed.  
3. If the exponent is negative, press ·, and then type the  
exponent, which can be one or two digits.  
Entering a number in scientific notation does not cause the  
answers to be displayed in scientific notation. The display  
format is determined by the mode settings (pages 1-9 through  
1-11) and the size of the number.  
Functions  
A function returns a value. For example, ÷, ×, , +, , and LOG  
are functions. Some functions take more than one argument,  
which is indicated by a ( at the end of the name. MIN( requires  
two arguments in this example: MIN(5,8).  
Instructions  
An instruction initiates an action. For example, CLRDRAW is  
an instruction that clears any drawn elements from a graph.  
Instructions cannot be used in expressions. Some instructions  
take more than one argument, which is indicated by a ( at the  
end of the name. LINE( requires four arguments in this  
example: LINE(1,1,3,3).  
Interrupting a  
Calculation  
While the busy indicator is displayed, indicating that a  
calculation or a graph is in progress, you can press ´ to stop  
the calculation. (There may be a delay.)  
Operating the TI-80 1-7  
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The Edit Keys  
The arrow keys near the upper right of the keyboard control the movement of  
the cursor. In normal entry, a keystroke types over the character or characters  
at the position of the cursor. The 4 and y / keys delete or insert  
characters.  
Key(s)  
Action(s)  
9 or 6  
Moves the cursor within an expression. These keys repeat  
when you hold them down.  
7 or 8  
Moves the cursor between lines within an expression. These  
keys repeat when you hold them down.  
¦
On the top line of an expression on the Home screen, 7  
moves the cursor to the beginning of the expression.  
¦
On the bottom line of an expression on the Home screen,  
8 moves the cursor to the end of the expression.  
2 6  
2 9  
¸
M
Moves the cursor to the beginning of an expression.  
Moves the cursor to the end of an expression.  
Evaluates an expression or executes an instruction.  
¦
¦
¦
On a line with text on the Home screen, clears (blanks) the  
current line.  
On a blank line on the Home screen, clears everything on  
the Home screen.  
In an editor, clears (blanks) the expression or value where  
the cursor is located; it does not store a zero.  
4
Deletes the character at the cursor. This key repeats.  
y /  
Lets you insert characters at the underline cursor. To end  
insertion, press y / or a cursor key.  
Next key press is a 2nd operation (the gold-colored label  
printed to the left above a key). The cursor changes to Ž. To  
cancel 2nd, press y again.  
y
?
Next key press is an ALPHA character (the light gray  
character to the right above a key). The cursor changes to A.  
To cancel ALPHA, press ? or a cursor key.  
y <  
Sets ALPHA-LOCK; each subsequent key press results in an  
ALPHA character. The cursor changes to . To cancel  
ALPHA-LOCK, press ?.  
@
Allows you to enter an X in FUNC mode or a T in PARAM  
mode without pressing ? first.  
1-8 Operating the TI-80  
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Setting Modes  
Modes control how numbers and graphs are displayed and interpreted by the  
calculator. Mode settings are retained by the Constant Memory feature when the  
TI.80 is turned off.  
Checking MODE Press 3 to display the MODE screen. The current settings  
Settings  
are highlighted. The settings are described on the following  
pages.  
NORMAL SCI  
Numeric display format.  
FLOAT 0123456789 Number of decimal places.  
RADIAN DEGREE  
aÀbºc bºc  
Unit of angle measure.  
Type of fraction display.  
AUTOSIMP MANSIMP Whether to simplify fractions.  
FUNC PARAM  
Type of graphing.  
CONNECTED DOT  
Whether to connect graph points.  
SEQUENTIAL SIMUL Whether to plot simultaneously.  
Changing MODE  
Settings  
To change the mode setting:  
1. Press 8 or 7 to move the cursor to the line of the setting  
that you want to change. The setting that the cursor is on  
blinks.  
2. Press 9 or 6 to move the cursor to the setting that you  
want.  
3. Press ¸.  
Leaving the  
To leave the MODE screen:  
MODE Screen  
¦
¦
Press the appropriate keys to go to another screen.  
Press y . or M to return to the Home screen.  
Setting a Mode  
from a Program  
You can set a mode from a program by entering the name of  
the mode as an instruction; for example, FUNC or FLOAT.  
From a blank line in the program editor (Chapter 10), press  
3 to display a menu of the mode names, and then select  
the name. The name is copied to the cursor location.  
Operating the TI-80 1-9  
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TI-80 Modes  
The TI.80 has eight mode settings. They control how numeric entries are  
interpreted, how answers are calculated or displayed, and how graphs appear in  
the display. Modes are set on the MODE screen (page 1.9).  
NORMAL  
SCI  
Notation formats affect only how an answer is displayed on  
the Home screen. Numeric answers can be displayed with up  
to 10 digits and a two-digit exponent. You can enter a number  
in any format.  
NORMAL display format is the way in which we usually  
express decimal numbers, with digits to the left and right of  
the decimal, as in 12345.67.  
SCI (scientific) notation expresses numbers in two parts. The  
significant digits can be displayed with one digit to the left of  
the decimal. The appropriate power of 10 displays to the right  
of í, as in 1.234567í4.  
Note: If you select normal display format, but the answer  
cannot be displayed in 10 digits or the absolute value is less  
than .001, the TI-80 displays the answer in scientific notation.  
FLOAT  
Fixed Decimal  
Decimal settings affect only how an answer is displayed on  
the Home screen. You can enter a number in any format. The  
decimal settings apply to both notation formats.  
FLOAT (floating) decimal setting displays up to 10 digits, plus  
the sign and decimal.  
The fixed decimal setting lets you select the number of digits  
(0 to 9) to be displayed to the right of the decimal. The  
displayed value is rounded based on the number of digits you  
selected. The actual value is stored and used in calculations.  
Place the cursor on the number of decimal digits you want,  
and press ¸.  
Note: In the program editor, the format for fixed decimal  
settings is FIX n. Enter n as an integer from 0 to 9. The mode  
is changed to fixed decimal when the program is executed.  
1-10 Operating the TI-80  
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RADIAN  
DEGREE  
The angle mode controls:  
¦
How the calculator interprets angle arguments in SIN,  
COS, TAN, and polar-to-rectangular conversions.  
How the calculator returns angle answers to SINê, COSê,  
TANê, and rectangular-to-polar conversions.  
¦
RADIAN mode interprets angle arguments as radians and  
returns angle answers in radians.  
DEGREE mode interprets angle arguments as degrees and  
returns angle answers in degrees.  
aÀbºc  
aÀbºc displays fraction results as mixed numbers; for  
bºc  
example, the result of 1º3 + 4º3 is displayed as 1À2º3.  
bºc displays fraction results as simple fractions; for example,  
the result of 1º3 + 4º3 is displayed as 5º3.  
AUTOSIMP  
MANSIMP  
AUTOSIMP automatically simplifies fraction results to their  
lowest terms before displaying them; for example, the result  
of 2º6 + 2º6 is displayed as 2º3.  
MANSIMP displays fraction results without automatic  
simplification; for example, the result of 2º6 + 2º6 is  
displayed as 4º6.  
FUNC  
FUNC (function) graphing plots functions where Y is  
PARAM  
expressed in terms of X (Chapter 4).  
PARAM (parametric) graphing plots relations where X and Y  
are each expressed in terms of T (Chapter 5).  
CONNECTED  
DOT  
CONNECTED draws line segments between the calculated  
points of the selected functions.  
DOT plots only the calculated points of the selected functions.  
SEQUENTIAL  
SIMUL  
SEQUENTIAL graphing evaluates and plots one function  
completely before the next function is evaluated and plotted.  
SIMUL (simultaneous) graphing evaluates and plots all  
selected functions for a single value of X, one at a time. In  
Parametric mode, X and Y are selected pairs. They are  
evaluated and plotted a T value at a time.  
Operating the TI-80 1-11  
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Variable Names  
On the TI.80 you can enter, name, and use several types of data: numeric values  
(including fractions), lists, functions, and statistical plots.  
Variables and  
Defined Items  
The TI-80 uses both user-assigned and pre-assigned names for  
variables and other items saved in memory.  
Variable Type  
Names  
Numeric values  
A, B, ..., Z, q (single character only).  
(including fractions)  
Lists  
L1, L2, L3, L4, L5, L6 (on the  
keyboard).  
Functions  
Y1, Y2, Y3, Y4 (on the Y= editor in  
FUNC mode).  
Parametric equations  
X1î/Y1î X2î/Y2î, X3î/Y3î (on the Y=  
editor in PARAM mode).  
Statistical plots  
System variables  
PLOT1, PLOT2, PLOT3 (on the  
STAT PLOTS menu).  
XMIN, XMAX, and others (on various  
menus).  
Programs have user-defined names also and share memory  
with variables. Program names can be up to seven characters  
long. Programs are entered and edited from the program  
editor (Chapter 10).  
You can store to lists (Chapter 8), system variables such as  
XMAX (Chapter 4) or TBLMIN (Chapter 6), and all Y=  
functions (Chapters 4 and 5) from the Home screen or from a  
program. You can store to lists (Chapters 8 and 9) and  
functions (Chapters 4 and 5) from editors. You can also store  
to a list element (Chapter 8).  
For more information about system variables, see Appendix A.  
1-12 Operating the TI-80  
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Storing and Recalling Variable Values  
Values are stored to and recalled from memory using variable names. When an  
expression containing the name of a variable is evaluated, the value of the  
variable at that time is used.  
Storing Values in You can store a value to a variable from the Home screen or a  
a Variable  
program using the § key. Begin on a blank line.  
1. Enter the value that you want to store (this can be an  
expression).  
2. Press §. The symbol ! is copied to the cursor location.  
3. Press ? and then the single letter of the variable to  
which you want to store the value.  
4. Press ¸. If you entered an expression, it is evaluated.  
The value is stored in the variable.  
Displaying a  
Variable Value  
To display the value of a variable, enter the variable name on a  
blank line on the Home screen, and then press ¸. You can  
enter the name of the variable in one of the following ways:  
¦
Press ? and the letter of the variable (for user-defined  
variables).  
¦
¦
Press 2 and the name of the list.  
Press L and select the type and name of the variable  
(for system variables).  
¦
Press 2 G and select the type and name of the  
function.  
Using a Variable To use the current value of a variable in an expression, just  
in an Expression enter the variable name in the expression.  
Operating the TI-80 1-13  
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Last Entry  
When you press ¸ on the Home screen to evaluate an expression or execute  
an instruction, the expression or instruction is stored in an area called Last  
Entry, which you can recall. When you turn the TI.80 off, Last Entry is retained in  
memory.  
Using Last Entry You can recall Last Entry and edit it from the Home screen.  
Press y ². The current line is cleared, and the Last  
Entry is copied to the line. The cursor is positioned at the end  
of the entry. Because the TI-80 updates the Last Entry storage  
area only when you press ¸, you can recall the previous  
entry even if you have begun entering the next expression.  
However, when you recall Last Entry, it replaces what you  
have typed.  
5 « 7  
¸
y ²  

The TI-80 keeps previous entries (up to a total of 80 bytes) in  
Last Entry. You can display and edit those entries by  
continuing to press 2 ². Last Entry displays previous  
entries in a loop, beginning with newest entry and moving to  
the oldest entry. Once the oldest item is displayed, 2 ²  
displays the newest item again.  
Displaying a  
Previous Entry  
1 § ? A  
¸
2 § ? B  
¸
3 § ? C  
¸

y ²  
When you press y ² again, the previous item replaces  
the item on the current line.  
2 ²  
1-14 Operating the TI-80  
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Re.executing the To execute Last Entry, press ¸ on a blank line on the  
Previous Entry  
Home screen. The entry is executed, but it does not display  
again.  
0 § ? N  
¸
? N « 1 § ? N  
¸
¸
¸

Multiple Entries  
on a Line  
To enter more than one expression or instruction on a line,  
separate them with a colon (:). They are all stored together in  
Last Entry.  
If the previous entry contained more than one expression or  
instruction, separated with a colon (page 1-6), they all are  
recalled. You can recall all entries on a line, edit any of them,  
and then execute all of them.  
Using the equation A=pr2, use trial and error to find the radius  
of a circle that covers 200 square centimeters. Use 8 as your  
first guess.  

8 § ? R y °  
y T ? R a  
¸
y ²  
Now try this.  
y 6 7 y / .95  
¸
Continue until the answer is as accurate as you want.  
Operating the TI-80 1-15  
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Last Answer  
When an expression is evaluated successfully from the Home screen or from a  
program, the TI.80 stores the answer to a variable, ANS (Last Answer). ANS may  
be a decimal number, a fraction, or a list. When you turn the TI.80 off, the value  
in ANS is retained in memory.  
Using Last  
You can use the variable ANS to represent the last answer in  
Answer (ANS) in most places. When you press y ±, the variable name ANS  
an Expression  
is copied to the cursor location. When the expression is  
evaluated, the TI-80 uses the value of ANS in the calculation.  
Calculate the area of a garden plot that is 1.7 meters by 4.2  
meters. Then calculate the yield per square meter if the plot  
produces a total of 147 tomatoes.  

1.7 p 4.2  
¸
147 e y ±  
¸
Continuing an  
Expression  
You can use the value in ANS as the first entry in the next  
expression without entering the value again or pressing y  
±. On a blank line on the Home screen, enter the function.  
The TI-80 “types” the variable name ANS followed by the  
function.  
5 e 2  
¸
p 9.9  
¸

Storing Answers To store an answer, store ANS to a variable before you  
evaluate another expression.  
Calculate the area of a circle of radius 5 meters. Then  
calculate the volume of a cylinder of radius 5 meters and  
height 3.3 meters. Store the result in the variable V.  

y T 5 a  
¸
p 3.3  
¸
§ ? V  
¸
1-16 Operating the TI-80  
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TI-80 Menus  
To leave the keyboard uncluttered, the TI.80 uses full.screen menus to give you  
access to many additional operations. The use of specific menus is described in  
the appropriate chapters.  
Moving from One Some menu keys, such as I, display more than one menu.  
Menu to Another The names of the menus appear on the top line. The current  
menu is highlighted and the items in that menu are displayed.  
Press 9 or 6 to move the cursor to a different menu.  
Selecting an Item The number of the current item is highlighted. If there are  
from a Menu  
more than seven items on the menu, a $ appears on the last  
line in place of the : (colon) between the menu number and  
name. Menu items, such as VARS WINDOW, that end in ...  
(ellipsis marks) display another menu.  
There are two methods of selecting from a menu.  
¦
¦
Press the number of the item you want to select.  
Press 8 and 7 to move the cursor to the item you want to  
select, and then press ¸.  
Calculate ò27 .  

1. Press I to display the MATH menu.  
2. To select ò, you may either press 4 or press 8 8 8  
¸.  
3. Enter 27, and then press ¸ to evaluate the expression.  
Operating the TI-80 1-17  
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Leaving a Menu  
There are several ways to leave a menu without making a  
without Making a selection from the menu.  
Selection  
¦
¦
¦
To return to the Home screen, press 2 ..  
To return to the screen where you were, press M.  
To display a different menu, press the appropriate key,  
such as *.  
¦
To select another screen, press the appropriate key, such  
as ).  
1-18 Operating the TI-80  
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The VARS and Y.VARS Menus  
You may want to use the names of system variables (such as XMIN) and  
functions (such as Y1) in an expression. You may also want to store values  
directly to those variables. Use the VARS or Y.VARS menus to access the  
names.  
VARS Menu  
The VARS menu displays the names of window variables such  
as XMIN and TSTEP, statistics variables such as v and Q1, and  
table variables such as TBLMIN.  
Press L to display the VARS menu. Some of the items  
display more than one menu of variable names.  
VARS  
1:WINDOW...  
2:STATISTICS... X/Y, G, EQ, and BOX variables.  
3:TABLE... TBLMIN and @TBL variables.  
Names of X, Y, and T variables.  
4:SIMPFACTOR... Factor last used by úSIMP function.  
Y.VARS Menu  
The Y.VARS menus display the names of functions and the  
instructions to select or deselect functions from a program or  
the Home screen.  
Press 2 G to display the Y.VARS menu. Then press 9  
or 6 to select the type of variable you want.  
Y
Displays a menu of names of Yn functions.  
XTàYT  
Displays a menu of names of XnTàYnT equations.  
ONàOFF Lets you select/deselect functions.  
Copying a Name To copy a variable name from a VARS or Y.VARS menu:  
from a VARS or  
Y.VARS Menu  
1. Press L or 2 G. The VARS or Y.VARS menu is  
displayed.  
2. Select the type of variable you want.  
3. Press ¸ to select the name you want from the menu. It  
is copied to the cursor location.  
Operating the TI-80 1-19  
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EOS (Equation Operating System)  
The Equation Operating System (EOS™) defines the order of operations for the  
calculator that is, the order in which the TI.80 evaluates functions in  
expressions. EOS lets you enter numbers and functions in a simple,  
straightforward sequence.  
Order of  
Evaluation  
A function returns a value. EOS evaluates the functions in an  
expression in the following order.  
1
Functions that are entered after the argument, such as  
Añ, 2ê, 22!, 45¡, 2pô, and úSIMP.  
2
3
Powers and roots, such as 2^5 or 5õ32.  
Implied multiplication where the second argument is a  
number, variable name, or list, or begins with an open  
parenthesis, such as 4A, (A+B)4, or 4(A+B).  
4
5
Single-argument functions that precede the argument,  
such as LA, 63, SIN B, or LOG 3.  
Implied multiplication where the second argument is a  
multi-argument function or a single-argument function  
that precedes the argument, such as 2NDERIV(Añ,A,6) or  
ASIN 2.  
6
7
8
9
Permutations (nPr) and combinations (nCr).  
Multiplication and division (including INT÷).  
Addition and subtraction.  
Test functions, such as > or .  
10 Conversion functions: 8FRAC, 8DEC, 8aÀbºc, and 8bºc.  
Within a priority group, EOS evaluates functions from left to  
right. However, two or more single-argument functions that  
precede the same argument are evaluated from right to left.  
For example, SIN FPART LN 8 is evaluated as  
SIN(FPART(LN 8)).  
Calculations within a pair of parentheses are evaluated first.  
Multi-argument functions, such as NDERIV(Añ,A,6), are  
evaluated as they are encountered.  
The conversion functions 8FRAC, 8DEC, 8aÀbºc, and 8bºc  
can be used only at the end of a command line with one  
exception: they can be followed by a store instruction.  
1-20 Operating the TI-80  
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Implied  
Multiplication  
The TI-80 recognizes implied multiplication. For example, it  
understands 2p, 4SIN 45, 5(1+2), and (2×5)7 as implied  
multiplication.  
Parentheses  
All calculations inside a pair of parentheses are completed  
first. For example, in the expression 4(1+2), EOS first  
evaluates the portion inside the parentheses, 1+2, and then  
multiplies the answer, 3, by 4.  
You can omit any right (closing) parenthesis at the end of an  
expression. All “open” parenthetical elements are closed  
automatically at the end of an expression and preceding the !  
(store) or display-conversion instructions.  
Note: Parentheses are also used to enclose the arguments for  
certain functions, for example, NDERIV(Añ,A,6). In these  
cases, parentheses do not indicate implied multiplication.  
Negation  
To enter a negative number, use the negation function. Press  
·, and then enter the number. On the TI-80, negation is in the  
fourth group in the EOS hierarchy. Functions in the first  
group, such as squaring, are evaluated before negation.  
For example, LXñ is a negative number (or 0); L9ñ is L81. Use  
parentheses to square a negative number: (L9)ñ.  
Note: Use the | key for subtraction and the · key for  
negation. If you press | to enter a negative number, as in 9 p  
| 7, or if you press · to indicate subtraction, as in 9 · 7, it  
is an error. If you press ? A · ? B, it is interpreted  
as implied multiplication (A QLB).  
Operating the TI-80 1-21  
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Error Conditions  
The TI.80 detects any errors at the time it evaluates an expression, executes an  
instruction, plots a graph, or stores a value. Calculations stop and an error  
message with a menu is displayed immediately. Error codes and conditions are  
described in detail in Appendix B.  
If the TI-80 detects an error, it displays the error screen.  
Diagnosing an  
Error  
The top line indicates the general type of error, such as  
SYNTAX or DOMAIN. For additional information about each  
error message, see Appendix B.  
¦
If you select GOTO, the cursor is displayed at the location  
where the error was detected.  
Note: If a syntax error was detected in the contents of a  
Y= function during program execution, GOTO returns the  
user to the Y= editor, not to the program.  
¦
If you select QUIT, or press y . or M, you return  
to the Home screen.  
Correcting an  
Error  
To correct an error:  
1. Note the type of the error.  
2. Select GOTO, if that option is available; and look at the  
expression for syntax errors, especially at and before the  
cursor location.  
3. If the error in the expression is not readily apparent, turn  
to Appendix B, and read the information about the error  
message.  
4. Correct the expression.  
1-22 Operating the TI-80  
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Chapter 2: Math, Angle, and Test Operations  
This chapter describes the math, angle, and relational operations that are  
available on the TI.80. The most commonly used functions are accessed from  
the keyboard; others are accessed through menus.  
Chapter  
Contents  
Getting Started: Lottery Chances ....................  
Using the TI-80 Functions..........................  
Keyboard Math Operations .........................  
MATH MATH Operations ...........................  
2-2  
2-3  
2-4  
2-7  
MATH NUM (Number) Operations ................... 2-10  
MATH PRB (Probability) Operations................. 2-12  
ANGLE Operations ................................ 2-14  
TEST (Relational) Operations....................... 2-16  
Math, Angle, and Test Operations 2-1  
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Getting Started: Lottery Chances  
Getting Started is a fast-paced introduction. Read the chapter for details.  
Suppose you want to enter a lottery where six numbers will be drawn out of 50.  
To win, you must pick all six numbers (in any order). What is the probability of  
winning if you buy one ticket? What is the probability of winning if you buy five  
tickets?  
1. Determine the number of combinations possible. On  
the Home screen, press 50 to enter the total number of  
items. Press I 6 to display the MATH PRB menu.  
Press 3 to select nCr. Press 6 to enter the number of  
items selected.  
2. Press ¸ to evaluate the expression. This is the  
total number of possible combinations of 6 numbers  
drawn from a set of 50 numbers. With one ticket, you  
have one chance in 15,890,700 of winning.  
3. To calculate the probability of winning with one  
ticket, press 1 e 2 ± ¸. The answer is too  
large to display in fixed notation; therefore, it is shown  
in scientific notation. 0.00000006292988981 is the  
decimal equivalent.  
4. To calculate the probability of winning with five  
tickets, press p 5 ¸. Again, the answer is too  
small to display in fixed notation. The decimal  
equivalent is 0.000000314649449.  
2-2 Math, Angle, and Test Operations  
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Using the TI-80 Functions  
This page contains some general information you should know about the TI.80  
functions described in Chapter 1.  
Using Lists with  
Functions  
Functions that are valid for lists return a list calculated on an  
element-by-element basis. If two lists are used in the same  
expression, they must be the same length. For more  
information about lists, see Chapter 8.  
Using Fractions  
with Functions  
Some math functions (+, , ×, à, xñ, úbºc, úaÀbºc, úDEC)  
accept fractions as input values. All other functions convert  
fractions to decimals before operating on them. For more  
information about fractions, see Chapter 3.  
Math, Angle, and Test Operations 2-3  
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Keyboard Math Operations  
The most commonly used math functions are on the keyboard. The keyboard  
math operations can be used with decimal numbers, fractions (except as noted),  
expressions, and lists.  
+ (Add)  
The basic arithmetic functions are: addition «, subtraction |,  
multiplication p, and division e. Each argument for these  
functions can be a list.  
(Subtract)  
× (Multiply)  
à (Divide)  
valueA+valueB, valueAìvalueB,  
valueA×valueB, valueAàvalueB  
Trig Functions  
The trigonometric functions are interpreted according to the  
current RADIAN/DEGREE mode setting. (Refer to page 1-9 for  
instructions on changing the mode setting.) For example,  
SIN 30 in RADIAN mode returns L.9880316241; in DEGREE  
mode, it returns .5. Each argument for the trigonometric  
functions may be a list.  
SIN value, COS value, TAN value  
SINê, COSê, and TANê are the inverse trig functions (arcsine,  
arccosine, and arctangent).  
SINê value, COSê value, TANê value  
RADIAN Mode  
ê (Inverse)  
ê (inverse, V) may be used with numbers, expressions, or  
lists. The multiplicative inverse is the equivalent of the  
reciprocal, 1àx.  
valueê  
2-4 Math, Angle, and Test Operations  
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^ (Power)  
^ (power, Z), 2 (square, a), and (square root, 2 ]) may  
be used with decimal numbers, fractions, expressions, or lists.  
When used with a fraction, returns a decimal number.  
2
(Square)  
(Square Root)  
value^power, value2, value  
Note: Raising a negative number to a noninteger power can  
result in a complex number, which returns an error.  
LOG  
10^  
LN  
These functions find the logarithm l, power of ten 2 h,  
and natural log x of the specified value or list of values.  
LOG value, 10^power, LN value  
e^ ( 2 s) returns the constant e raised to a power or list of  
e^  
powers. e^1 returns the value of the constant e.  
e^power  
Math, Angle, and Test Operations 2-5  
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L
(Negation)  
L (negation, ·) returns the negative of a number, expression,  
or list. The narrow negation symbol (L) distinguishes negation  
from the subtraction or minus ().  
Lvalue  
EOS rules (Chapter 1) determine when negation is evaluated.  
For example, LA2 returns a negative number because squaring  
is evaluated before negation. Use parentheses to square a  
negated number, (LA)2.  
ABS  
ABS (absolute value, 2 P) returns the absolute value of a  
number, expression, or list.  
ABS value  
p (Pi)  
Pi (2 T) is stored as a constant in the TI-80. Press 2 T  
to copy the symbol p to the cursor location. The number  
3.141592654 is displayed for p, but 3.1415926535898 is used  
internally in calculations.  
2-6 Math, Angle, and Test Operations  
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MATH MATH Operations  
To display the MATH MATH menu, press I. When you select a menu item, the  
name is copied to the cursor location. Functions that are valid for lists return a  
list calculated on an element-by-element basis.  
MATH MATH  
Menu  
MATH NUM PRB  
1:  
2:  
3:  
4:  
5:  
Displays quotient and remainder.  
Displays answer in decimal form.  
Cube.  
INT÷  
8DEC  
3
3
Cube root.  
n
th root.  
x
6:NDERIV(  
Numerical derivative.  
INT÷  
On the Home screen or from a program, INT÷ (integer divide,  
MATH MATH, item 1) returns the quotient (or quotient and  
remainder) resulting from the division of two integers. Each  
argument can be a list.  
integerAINT÷integerB  
When INT÷ is executed on the Home screen, it displays the  
symbols Q= for the quotient and R= for the remainder.  
Note: If INT÷ is embedded in an expression, Q= and R= may  
not be displayed.  
When used with lists, INT÷ returns a list of quotients only.  
If the result of INT÷ is used in subsequent calculations, the  
remainder is dropped, and only the quotient is used.  
The quotient from INT÷ is returned to ANS.  
Math, Angle, and Test Operations 2-7  
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8DEC  
8DEC (convert to decimal, MATH MATH, item 2) displays an  
answer in decimal form. 8DEC can only be used after a value  
and at the end of an expression. value can be a list.  
value8DEC  
expression8DEC  
3
3
(Cube)  
(cube, MATH MATH, item 3) returns the cube of a number,  
expression, or list.  
3
value  
3
3(Cube Root)  
(cube root, MATH MATH, item 4) returns the cube root of a  
number, expression, or list.  
3
value  
x(Root)  
(root, MATH MATH, item 5) returns the nth real root of a  
x
number, expression, or list.  
th  
x
n root value  
2-8 Math, Angle, and Test Operations  
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NDERIV(  
NDERIV( (numerical derivative, MATH MATH, item 6) returns  
an approximate derivative of an expression with respect to a  
specified variable, given the value at which to calculate the  
-
derivative, and H (optional; if none is specified, 1í 3 is used).  
NDERIV(expression,variable,value) or  
NDERIV(expression,variable,value,H)  
NDERIV( uses the symmetric difference quotient method (as  
shown in the formula below), which approximates the  
numerical derivative value as the slope of the secant line  
through the points:  
f(X+H)–f(XH)  
f¢(x) =  
2H  
As H gets smaller, the approximation usually gets more  
accurate.  
Because of the method used, NDERIV( can return a false  
derivative value at a nondifferentiable point.  
Math, Angle, and Test Operations 2-9  
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MATH NUM (Number) Operations  
To display the MATH NUM menu, press I 9. When you select a menu item,  
the name is copied to the cursor location. Functions that are valid for lists return  
a list calculated on an element-by-element basis.  
MATH NUM  
Menu  
MATH NUM PRB  
1:ROUND(  
2:IPART  
3:FPART  
4:INT  
5:MIN(  
6:MAX(  
Round.  
Integer part.  
Fractional part.  
Greatest integer.  
Minimum value.  
Maximum value.  
7:REMAINDER( Remainder of a division result.  
ROUND(  
ROUND( (MATH NUM, item 1) returns a number, expression,  
or list rounded to a specified number of decimals (9). If the  
number of decimals is omitted, the number is rounded to the  
digits that are displayed, a maximum of 10 digits.  
Round(value,#decimals)  
Round(value)  
ZPART  
FPART  
ZPART (integer part, MATH NUM, item 2) returns the integer  
part or parts of a number, expression, or list. FPART  
(fractional part, MATH NUM, item 3) returns the fractional  
part or parts of a number, expression, or list.  
ZPART value  
FPART value  
INT  
INT (greatest integer, MATH NUM, item 4) returns the largest  
integer less than or equal to a number, expression, or list. The  
value is the same as ZPART for nonnegative numbers and  
negative integers, but one integer less than ZPART for negative  
noninteger numbers.  
INT value  
2-10 Math, Angle, and Test Operations  
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MIN(  
MAX(  
MIN( (minimum value, MATH NUM, item 5) returns the smaller  
of two values or the smallest element in a list. If two lists are  
compared, it returns a list of the smaller of each pair of  
elements. If a list and a value are compared, it compares each  
element in the list to the value.  
MAX( (maximum value, MATH NUM, item 6) returns the larger  
of two values or the largest element in a list. If two lists are  
compared, it returns a list of the larger of each pair of  
elements. If a list and a value are compared, it compares each  
element in the list to the value.  
MIN(valueA,valueB)  
MIN(list)  
MAX(valueA,valueB)  
MAX(list)  
MIN(listA,listB)  
MIN(value,list)  
MIN(list,value)  
MAX(listA,listB)  
MAX(value,list)  
MAX(list,value)  
Note: MIN( and MAX( are also available on the LIST MATH  
menu.  
REMAINDER(  
REMAINDER( (MATH NUM, item 7) returns the remainder  
resulting from the division of two integers, each of which can  
be a list. (See INT÷, page 2–7.)  
REMAINDER(valueA,valueB)  
REMAINDER(listA,listB)  
REMAINDER(value,list)  
REMAINDER(list,value)  
If a list is used as one or both arguments, the result is a list of  
remainders.  
Math, Angle, and Test Operations 2-11  
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MATH PRB (Probability) Operations  
To display the MATH PRB menu, press I 6. When you select a menu item,  
the name is copied to the cursor location. Functions that are valid for lists return  
a list calculated on an element-by-element basis.  
MATH PRB  
Menu  
MATH NUM PRB  
1:RAND  
2:nPr  
3:nCr  
4:!  
Random number generator.  
Number of permutations.  
Number of combinations.  
Factorial.  
5:RANDINT(  
Random integer generator.  
RAND  
RAND (random number, MATH PRB, item 1) generates and  
returns a random number greater than 0 and less than 1 (as in  
the first example below). A random number is generated from  
a seed value. To control a random number sequence, first  
store an integer seed value in RAND. In the second example  
below, 1 is stored to RAND so that the TI-80 uses 1 as the seed  
value for generating random numbers.  
Note: When you reset the TI-80, RAND is set to the factory  
seed value, which is 0.  
2-12 Math, Angle, and Test Operations  
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nPr  
nCr  
nPr (number of permutations, MATH PRB, item 2) returns the  
number of permutations of items taken number at a time.  
items and number must be nonnegative integers. Both items  
and number can be lists.  
nCr (number of combinations, MATH PRB, item 3) returns the  
number of combinations of items taken number at a time.  
items and number must be nonnegative integers. Both items  
and number can be lists.  
items nPr number  
items nCr number  
! (Factorial)  
! (factorial, MATH PRB, item 4) returns the factorial of a  
positive integer or list of integers between 0 and 69.  
value!  
RANDINT(  
RANDINT( (random integer, MATH PRB, item 5) generates a  
random integer within a specified range. It requires two  
arguments: the lower and upper boundaries of the range (in  
any order). Both arguments must be integers. Both arguments  
can be negative. Both arguments can be lists.  
RANDINT(lower,upper)  
Math, Angle, and Test Operations 2-13  
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ANGLE Operations  
To display the ANGLE menu, press 2 E. The ANGLE menu displays angle  
indicators and instructions. When you select an item from the menu, the name is  
copied to the cursor location.  
ANGLE  
Menu  
ANGLE  
1:  
2:  
Degree notation.  
Radian notation.  
¡
r
3:R8Pr(  
4:R8Pq(  
5:P8Rx(  
6:P8Ry(  
Returns r, given X and Y.  
Returns q, given X and Y.  
Returns x, given R and q.  
Returns y, given R and q.  
°(Degree)  
¡ (degree, ANGLE, item 1) lets you designate an angle or list of  
angles as degrees, regardless of the current angle mode  
setting. In RADIAN mode, ¡ can also be used to convert  
degrees to radians.  
value¡  
RADIAN Mode  
r
r
(Radians)  
(radians, ANGLE, item 2) lets you designate an angle or list  
of angles as radians, regardless of the current angle mode  
r
setting. In DEGREE mode, can also be used to convert  
radians to degrees.  
r
value  
DEGREE Mode  
2-14 Math, Angle, and Test Operations  
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R8Pr (  
R8Pq(  
P8Rx(  
P8Ry(  
Note: When converting from one coordinate system to the  
other, be sure that the angle mode setting, DEGREE or  
RADIAN, is appropriate for your angle measurements. (Press  
3 to check the current setting.)  
R8Pr( (ANGLE, item 3) converts the given rectangular  
coordinates to polar coordinates and returns r.  
R8Pq( (ANGLE, item 4) converts the given rectangular  
coordinates to polar coordinates and returns q.  
Both X and Y can be lists.  
R8Pr(X,Y)  
R8Pq(X,Y)  
RADIAN Mode  
P8Rx( (ANGLE, item 5) converts the given polar coordinates  
to rectangular coordinates and returns x.  
P8Ry( (ANGLE, item 6) converts the given polar coordinates  
to rectangular coordinates and returns y.  
Both R and q can be lists.  
P8Rx(R,q)  
P8Ry(R,q)  
RADIAN Mode  
Math, Angle, and Test Operations 2-15  
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TEST (Relational) Operations  
To display the TEST menu, press 2 D. When you select from the menu, the  
name is copied to the cursor location. These functions are valid for lists; they  
return a list calculated on an element-by-element basis.  
TEST Menu  
TEST True if:  
1:=  
2:ƒ  
3:>  
4:‚  
5:<  
6:  
Equal.  
Not equal to.  
Greater than.  
Greater than or equal to.  
Less than.  
Less than or equal to.  
=
ƒ
>
<

Relational operators compare valueA and valueB and return 1  
if the test is true or 0 if the test is false. valueA and valueB can  
be numbers, expressions, or lists.  
Relational operators are often used in programs to control  
program flow and in graphing to control the graph of a  
function over specific values.  
valueA=valueB  
valueAƒvalueB  
valueA>valueB  
valueAvalueB  
valueA<valueB  
valueAvalueB  
Using Tests  
Relational operators are evaluated after mathematical  
functions according to EOS rules (Chapter 1).  
¦
The expression 2+2=2+3 returns 0. The TI-80 does the  
addition first because of EOS rules, and then it compares 4  
to 5.  
¦
The expression 2+(2=2)+3 returns 6. The TI-80 first  
performs the relational test because it is in parentheses;  
then it adds 2, 1, and 3.  
2-16 Math, Angle, and Test Operations  
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Chapter 3: Fractions  
This chapter describes how to use the fraction operations on the TI.80.  
Chapter  
Contents  
Getting Started: Working with Fractions .............  
Setting Modes for Fraction Results ..................  
Entering and Using Fractions in Calculations .........  
The FRACTION Menu..............................  
3-2  
3-4  
3-6  
3-8  
Fractions 3-1  
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Getting Started: Working with Fractions  
Getting Started is a fast-paced introduction. Read the chapter for details.  
Enter the expression 1 6/27 + 1 1/9. Evaluate the expression, simplify the result,  
and then use the conversion options on the FRACTION menu to convert the  
result.  
This example is performed in MANSIMP (manual simplification) mode. MANSIMP  
mode is especially useful for students when they are learning fraction concepts.  
When MANSIMP mode is selected, the úSIMP function (from the FRACTION  
menu) can be used to simplify fractions step-by-step.  
1. Select MANSIMP mode.  
2. From the Home screen, press 1 2 ¥ 6 2 _  
27 « 1 2 ¥ 1 2 _ 9 to enter the mixed-  
fraction expression, 1 6/27 + 1 1/9.  
3. Press ¸ to evaluate the expression. The ï  
indicates that the fraction can be simplified.  
4. Press J 1 to select úSIMP (simplify). ANSúSIMP  
is copied to the cursor location.  
5. Press ¸ to simplify the fraction.  
In MANSIMP mode, the TI-80 uses the lowest  
common factor for simplification. The simplification  
factor is displayed. The ï preceding the result  
indicates that the fraction can be simplified further.  
Continue pressing ¸ until ï is no longer  
displayed.  
3-2 Fractions  
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The TI.80 uses the lowest common factor for simplification. If you want to  
choose the simplification factor yourself, you can enter it as part of the  
expression.  
6. Press M to clear the screen. Reenter the  
expression, or press 2 ² until you see the  
expression 1À6º27 + 1À1º9.  
7. Press 2 6 2 / c 2 9 b 9 d. This adds the  
simplification factor 9 and places the expression in  
parentheses.  
8. Press J 1 to copy úSIMP to the cursor location.  
9. Press ¸ to simplify the fraction result. The  
simplification factor is displayed.  
10. Press 2 ± J 2 ¸ to convert the mixed  
fraction result to a simple fraction.  
11. Press 2 ± J 5 ¸ to convert the fraction  
result to its decimal equivalent.  
Fractions 3-3  
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Setting Modes for Fraction Results  
From the MODE screen, you can select simplification and display format options  
for fraction results.  
AUTOSIMP Mode AUTOSIMP mode simplifies fractions automatically.  
with bºc and  
aÀbºc Modes  
Simplification takes place before the expression is evaluated.  
Then the result is simplified to its lowest terms. For example,  
12à16 is simplified to 3à4 when you press ¸.  
There are two formats for displaying fractions results.  
¦
bºc mode displays fraction results in simple-fraction (a  
fraction without a whole number) format; for example,  
25à4.  
¦
aÀbºc displays fraction results in mixed-fraction (a whole  
number with a fraction) format; for example 5 3/4.  
3-4 Fractions  
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MANSIMP Mode  
MANSIMP mode lets you simplify fractions manually.  
with aÀbºc Mode MANSIMP was designed for teaching and learning fractions  
concepts. In MANSIMP mode, you can simplify fractions and  
the results of expressions using fractions, step-by-step.  
When a fraction result is not expressed in its lowest terms, a  
down arrow (ï) is displayed to remind you that you can  
simplify the result. Use úSIMP from the FRACTION menu to  
simplify the fraction. You can then use úbºc or úaÀbºc to  
change the display format of the fraction result.  
Typically, you use the MANSIMP simplification mode with the  
úaÀbºc display format mode for teaching or learning fraction  
concepts. The display format of fraction results can vary when  
you are using MANSIMP and úaÀbºc.  
¦
When you simply enter a fraction and press ¸, the  
format in which you entered the fraction is preserved.  
¦
When you add or subtract using a mixed fraction,  
calculation takes place on the whole-number and  
fractional part of the mixed-fraction separately. The result  
is displayed as a mixed fraction.  
¦
When you multiply or divide using a mixed fraction, the  
result is displayed as a simple fraction.  
Fractions 3-5  
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Entering and Using Fractions in Calculations  
The TI.80 lets you enter fractions directly from the keyboard.  
Entering Simple  
Fractions  
A simple fraction is a fraction with no whole-number part; for  
example, 3à4 or 4à3.  
To enter a simple fraction:  
1. Enter the numerator (up to six digits), and then press 2  
_.  
2. Enter the denominator (up to and including 1000).  
For example, press 2 2 _ 3 to enter 2à3.  
Entering Mixed  
Fractions  
A mixed fraction is fraction that has both a whole-number and  
a fractional part; for example 1 1à3.  
To enter a mixed fraction:  
1. Enter the units (up to three digits), and then press 2  
¥.  
2. Enter the numerator (up to three digits), and then press  
2 _.  
3. Enter the denominator (up to and including 1000).  
For example, press 5 2 ¥ 2 2 _ 3 to enter 5 2à3.  
3-6 Fractions  
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In general, you can use fractions in expressions just as you would use other  
numbers. The results of the expressions, however, may or may not be fractions.  
Using Fractions  
in Expressions  
The absolute value of a fraction on the TI-80 cannot be 1000.  
«, |, p, e, V, a, ·, and 2 P accept fraction entries  
and return fraction results. If the absolute value of a fraction  
result is 1000, or if the results of operations with these  
functions are not within the limits shown on page 3-6, the  
results are given in decimal form.  
Other functions accept fraction entries, but convert them to  
decimal form before operating on them. The results are given  
in decimal form. For example, 4à9 returns .6666666667, not  
2à3.  
If you use úSIMP with a fraction that has been converted to a  
decimal, an error occurs.  
If an expression contains both a fraction and a decimal  
number, the result is displayed as a decimal number.  
You can also enter fractions in a list, but the results are  
returned as decimal values.  
Fractions 3-7  
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The FRACTION Menu  
To display the FRACTION menu, press J. The menu items let you simplify  
and convert fractions. When you select a menu item, the name is copied to the  
cursor location.  
FRACTION Menu  
FRACTION  
1: 8SIMP Simplifies the fraction.  
2: 8bºc  
Converts to a simple fraction.  
3: 8aÀbºc Converts to a mixed fraction.  
4: 8FRAC Converts a decimal to a fraction based on mode.  
5: 8DEC  
Converts a fraction to a decimal.  
Simplifying  
Fractions  
úSIMP  
úSIMP (simplify fraction, FRACTION, item 1) simplifies the  
specified fraction and displays it, along with the simplification  
factor.  
Note: úSIMP can only be used in MANSIMP mode.  
You have two options for simplifying fractions.  
¦
You can let the calculator simplify the fraction, step-by-  
step, using the lowest common factor (LCF).  
fractionúSIMP  
¦
You can choose a factor (an integer) for simplifying the  
fraction.  
(fraction,factor)úSIMP  
Both simplification options update the variable FACTOR.  
3-8 Fractions  
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Converting  
Simple and  
Mixed Fractions  
úbºc  
8bºc (convert to simple fraction, FRACTION, item 2) converts  
value to a simple fraction.  
8aÀbºc (convert to mixed fraction, item 3) converts value to a  
mixed fraction.  
8aÀbºc  
value8bºc  
value8aÀbºc  
Both 8bºc and 8aÀbºc can be used only at the end of an  
expression. A ! (§) instruction, however, can follow them.  
Fractions 3-9  
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Converting  
Decimals and  
Fractions  
úFRAC  
8FRAC (convert to fraction, FRACTION, item 4) converts a  
decimal value to its fraction equivalent and displays it. The  
decimal may be a number, expression, or list.  
In MANSIMP mode, 8FRAC first attempts to return a fraction  
in terms of 10ths, 100ths, or 1000ths. If this is not possible,  
8FRAC converts the decimal to its fraction equivalent as it  
would in AUTOSIMP mode. If the value cannot be converted  
or if the denominator of the equivalent fraction is greater than  
1000, the decimal equivalent is returned.  
8DEC  
The form of the 8FRAC result depends on the current fraction  
display format. For example, 1.25 8FRAC returns 1 1à4 if  
aÀbºc is selected or 5à4 if bºc is selected.  
If the decimal value for 8FRAC is a list, the list is displayed as  
fractions, but it is still stored internally in decimal form.  
8DEC (convert to decimal, FRACTION, item 5) converts a  
fraction value to its decimal form and displays it.  
decimal8FRAC  
fraction8DEC  
AUTOSIMP & aÀbºc  
AUTOSIMP & bºc  
MANSIMP & aÀbºc  
MANSIMP & bºc  
Both 8FRAC and 8DEC are valid only at the end of an  
expression. A ! (§) instruction, however, can follow them.  
3-10 Fractions  
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Chapter 4: Function Graphing  
This chapter describes function graphing on the TI.80 in detail. It also lays the  
foundation for using the parametric graphing features described in Chapter 5.  
Chapter  
Contents  
Getting Started: Graphing a Circle...................  
Defining a Graph..................................  
Setting Graph Modes ..............................  
Defining Functions in the Y= List....................  
Evaluating Y= Functions in Expressions .............  
Selecting Functions ...............................  
Defining the Viewing Window ......................  
4-2  
4-3  
4-4  
4-5  
4-7  
4-8  
4-9  
Displaying a Graph ................................ 4-11  
Exploring a Graph with the Free-Moving Cursor ...... 4-12  
Exploring a Graph with TRACE ..................... 4-13  
Exploring a Graph with ZOOM...................... 4-15  
Setting the Zoom Factors .......................... 4-18  
Function Graphing 4-1  
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Getting Started: Graphing a Circle  
Getting Started is a fast-paced introduction. Read the chapter for details.  
Graph a circle of radius 10, centered on the origin in the standard viewing  
window. To graph a circle, you must enter separate formulas for the upper and  
lower portions of the circle. Then use ZSQUARE to adjust the display to make  
the functions appear as a circle.  
Make sure that your TI-80 is in FUNC mode and all  
STAT PLOTS are turned off.  
1. Press ( to display the Y= edit screen. Press 2 ]  
c 100 | @ a d ¸ to enter the expression  
Y1=(100–X2), which defines the top half of the  
circle.  
The bottom half of the circle is defined by  
Y2=(100–X2). However, you can also define  
one function in terms of another; so to define  
Y2=LY1, press · 2 G (to display the Y=  
variables menu) 1 (to select Y1).  
2. Press * 6 to select ZSTANDARD. This is a quick  
way to reset the Window variables to the standard  
values. It also graphs the functions; you do not need  
to press ,.  
Notice that the functions appear as an ellipse in  
the standard viewing window.  
3. To adjust the display so each “dot” represents an  
equal width and height, press *, and then 5 to  
select ZSQUARE. The functions are replotted and  
now appear as a circle on the display.  
4. To see the ZSQUARE Window variables, press  
) and notice the values for XMIN, XMAX, YMIN,  
and YMAX.  
5. If you want to see the graph again, press ,.  
4-2 Function Graphing  
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Defining a Graph  
To define a graph, you set the modes, enter and select the functions to graph,  
and define the viewing window and the graphing format. Once you have defined  
a graph, you can plot it, display it, and explore it.  
Steps in Defining There are six basic steps to defining a graph, although you  
a Graph  
may not need to do all of the steps each time you define a  
graph. The procedures are described in detail on the following  
pages.  
1. Set the mode to FUNC graphing (Chapter 1).  
2. Enter or edit a function in the Y= list (page 4-5).  
3. Select the Y= function you want to graph (page 4-8).  
4. Define the viewing window (page 4-9).  
5. Set the graphing format (page 4-11).  
6. Deselect STAT PLOTS, if appropriate (Chapter 9).  
Exploring a  
Graph  
Once you have defined a graph, you can display it and use  
several tools on the TI-80 to explore the behavior of the  
function or functions. These tools are described later in this  
chapter.  
Function Graphing 4-3  
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Setting Graph Modes  
Pressing 3 displays the current mode settings, as described in Chapter 1. For  
function graphing, the graphing mode must be set to FUNC. Before you graph a  
function, check to be sure that the mode settings are appropriate.  
Checking and  
Changing  
Press 3 to display the mode settings. The current settings  
are highlighted.  
Graphing Modes  
The TI-80 has two graphing modes.  
¦
¦
FUNC (function graphing)  
PARAM (parametric graphing)  
To graph functions, you must select FUNC (function  
graphing).  
The basics of graphing on the TI-80 are described in this  
chapter. Differences in parametric graphing are described in  
Chapter 5.  
The mode settings can affect how functions are graphed.  
¦
¦
¦
RADIAN or DEGREE mode may affect how some functions  
are interpreted.  
CONNECTED or DOT affects how the selected functions  
are plotted.  
SEQUENTIAL or SIMUL affects how functions are plotted  
if you have more than one function selected.  
Setting Modes  
from a Program  
You can set the graphing mode and other modes from a  
program.  
Begin on a blank line in the program editor. Press 3 to  
display the MODE screen. Press 8 and 7 to place the cursor  
on the mode that you want to select, and then press ¸.  
The name of the mode is copied to the cursor location.  
4-4 Function Graphing  
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Defining Functions in the Y= List  
Pressing ( displays the Y= edit screen. This is where you enter the functions to  
graph. You can store up to four functions in memory at one time. You can graph  
one or more of these functions at a time.  
Displaying the  
Functions in the  
Y= List  
Press ( to display the Y= edit screen. In the example below,  
the Y1 and Y2 functions are defined.  
Defining a New  
Function  
To define a new function in the Y= list:  
1. Press ( to display the Y= edit screen.  
2. Move the cursor to the function in the Y= list you want to  
define. If necessary, press M to erase a previously  
entered function.  
3. Enter the expression to define the function.  
¦
¦
¦
You may use functions and variables in the expression.  
If the expression evaluates to a value that is not a real  
number, that point is not plotted; an error does not  
occur.  
The independent variable in the function is X. You may  
press @, rather than pressing ? ãXä, to enter the X  
variable. (FUNC mode defines the independent variable  
as X.)  
The expression is stored as one of the four user-defined  
functions in the Y= list as you enter it.  
Note: You can use a list within a Y= function; however,  
the function must evaluate to a single value.  
4. When you complete the expression, press ¸ to move  
to the beginning of the next function.  
Note: When you enter a function, it is automatically selected  
for graphing in the Y= list. This is indicated by the highlighted  
equal sign. For details on selecting and deselecting functions,  
see page 4-8.  
Function Graphing 4-5  
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Editing a  
Function  
To edit a function in the Y= list:  
1. Press ( to display the Y= list, and move the cursor to the  
function you want to change.  
2. Make the changes. You can also press M to erase the  
expression, and then enter a new expression.  
The expression is stored in the Y= list and selected (turned  
on) as you edit it.  
Clearing a  
Function  
To clear or erase a function on the Y= edit screen, position the  
cursor anywhere on the function, and then press M.  
To define a function from the Home screen or from a program,  
begin on a blank line.  
Defining  
Functions from  
the Home Screen  
or a Program  
1. Press ? ã"ä, enter the expression, and then press  
? ã"ä again.  
2. Press §.  
3. Press 2 G, and then select the name of the function  
from the Y menu. The name is copied to the cursor  
location.  
4. Press ¸ to complete the instruction.  
"expression"!Yn  
When the instruction is executed, the TI-80 stores the  
expression in the Y= list, selects (turns on) the function, and  
displays the message DONE.  
Leaving the Y=  
Edit Screen  
To leave the Y= edit screen:  
¦
Select another screen by pressing the appropriate key,  
such as , or ).  
¦
Press 2 . to return to the Home screen.  
4-6 Function Graphing  
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Evaluating Y= Functions in Expressions  
You can the calculate the value of a Y= function at a specified value of X.  
Entering the  
Functions in the  
Y= List  
To display the Y= list, press (. Enter these functions for Y1,  
Y2, and Y3: X2, X+2, and Y1(Y2(X)).  
@ a ¸  
@ « 2 ¸  
2 G 1 c 2 G 2  
c @ d d  

Evaluating  
Functions  
To evaluate the functions, first specify the value of X. Note  
that X may be a list.  
2 . M 2 G 2 c 3 d  
¸
2 G 1 c 2 G 2 c 3 d d  
¸
2 G 3 c 2 [ 1 , 2 , 3 2 \ d  
¸

Evaluating  
Functions  
without  
You can also evaluate functions without using parentheses by  
storing a value to X.  
3 § @ ¸  
2 G 1 ¸  
Parentheses  

Function Graphing 4-7  
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Selecting Functions  
Only functions that are selected (turned on) are graphed. All four functions may  
be selected at one time.  
Turning a  
You can select and deselect (“turn on” and “turn off”)  
Function “On” or functions on the Y= edit screen. The = sign on a selected  
“Off”  
function is highlighted.  
To change the selection status of a function:  
1. Display the Y= list, and move the cursor to the function  
whose status you want to change.  
2. Press 6 to place the cursor over the = sign of the function.  
3. Press ¸ to change the status. If the function was  
selected, it is now deselected. If it was deselected, it is  
now selected.  
Note: When you enter or edit a function, it is selected  
automatically. When you clear a function, it is deselected.  
Selecting  
To select functions from the Home screen or a program, begin  
on a blank line.  
Functions from  
the Home Screen  
or a Program  
1. Press 2 G, and then press 6 to select ON/OFF. The  
ON/OFF menu is displayed.  
2. Select the instruction you want, FNON or FNOFF. It is  
copied to the cursor location.  
3. To turn specific functions on or off, enter the number(s) of  
the function(s), separated by commas.  
FNON function#,function#, . . .  
FNOFF function#,function#, . . .  
For example, in FUNC mode, FNOFF 1,3 turns off functions  
Y1 and Y3.  
4-8 Function Graphing  
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Defining the Viewing Window  
The Window variables determine the boundaries and other attributes of the  
viewing window. The Window variables are shared by all graphing modes.  
The Viewing  
Window  
The viewing window of the TI-80 is the portion of the  
coordinate plane defined by XMIN, XMAX, YMIN, and YMAX.  
The distance between tick marks is defined by XSCL for the X  
axis and YSCL for the Y axis.  
YMAX  
XSCL  
XMIN  
XMAX  
YSCL  
YMIN  
Press ) to display the current Window variable values.  
Checking the  
The values shown here are the default values.  
Viewing Window  
Changing a  
Window Variable  
Value  
To change a Window variable value:  
1. Press 8 to move to the Window variable you want to  
change.  
2. To enter a real value (which can be an expression), you  
may do any of the following:  
¦
Position the cursor, and then make the changes.  
¦
Press M to clear the value, and then enter a new  
value.  
¦
Begin entering a new value. The original value is cleared  
automatically when you begin typing.  
3. Press ¸, 8, or 7. If you entered an expression, it is  
evaluated. The new value is stored.  
XMIN must be less than XMAX, and YMIN must be less than  
YMAX, or you will get an error message when you press  
,. To turn off the tick marks, set XSCL=0 and YSCL=0.  
Function Graphing 4-9  
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Leaving the  
To leave the Window screen:  
Window Screen  
¦
¦
Select another screen by pressing the appropriate key,  
such as , or (.  
Press 2 . to return to the Home screen.  
Storing to a  
To store to a Window variable from the Home screen or from  
Window Variable a program, begin on a blank line.  
from the Home  
Screen or a  
Program  
1. Enter the value (which can be an expression) that you  
want to store.  
2. Press §.  
3. Press L to display the VARS menu.  
4. Select WINDOW... to display the Window variables.  
5. Select the Window variable. The name of the variable is  
copied to the cursor location.  
6. Press ¸ to complete the instruction.  
Note: You can use a Window variable in an expression by  
performing steps 3, 4, and 5.  
@X and @Y  
The variables @X and @Y define the distance between the  
centers of two adjoining pixels on a graph (graphing  
accuracy).  
(XMAX – XMIN)  
(YMAX – YMIN)  
@X =  
@Y =  
62  
46  
@X and @Y are not on the Window screen; however, they are  
accessible through the VARS WINDOW... menu. @X and @Y are  
calculated from XMIN, XMAX, YMIN, and YMAX when a graph  
is displayed.  
You can store values directly to @X and @Y (7 and 8 on the  
VARS WINDOW... menu), in which case XMAX and YMAX are  
immediately calculated from @X, XMIN, @Y, and YMIN.  
4-10 Function Graphing  
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Displaying a Graph  
Pressing , graphs any functions selected on the Y= edit screen. The current  
mode settings apply, and the current values of the Window variables define the  
viewing window.  
Turning the Grid Grid points correspond to the axis tick marks. To turn the grid  
Points On and  
points on and off use GRIDON and GRIDOFF. The default for  
Off  
the TI-80 is GRIDOFF.  
1. From the Home screen, press 2 F to display the  
DRAW menu.  
2. Press 9 to select GRIDON, or press 0 to select GRIDOFF.  
3. Press ¸. The message DONE is displayed.  
Displaying a New Press , to display the graph of the selected function or  
Graph  
functions. (Some operations, such as TRACE and the Zoom  
instructions, display the graph automatically.) As a graph is  
plotted, the busy indicator is on, and X and Y are updated.  
Smart Graph  
When you press ,, Smart Graph displays the graph  
screen immediately if nothing has changed that requires the  
functions to be replotted since the last time the graph was  
displayed.  
If you have changed any of the following since the graph was  
last displayed, pressing , replots the graph based on the  
new values.  
¦
¦
¦
¦
¦
¦
¦
Changed a mode setting that affects graphs.  
Changed a function in the current picture.  
Deselected a function in the current picture.  
Changed the value of a variable in a selected function.  
Changed a Window variable or format setting.  
Cleared drawings by selecting CLRDRAW (Chapter 7).  
Changed or turned off a STAT PLOT definition (Chapter  
9).  
Note: CLRDRAW is a fast way to replot a graph.  
Overlaying  
Functions on a  
Graph  
The TI-80 lets you graph one function at a time without  
replotting every function. For example, enter SIN X as Y1 and  
press ,. Then enter COS X as Y2 and press , again.  
The second function is graphed on top of the original function.  
Function Graphing 4-11  
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Exploring a Graph with the Free-Moving Cursor  
While a graph is displayed, you can move the free-moving cursor anywhere on  
the graph and display the coordinates of any location on the graph.  
Free-Moving  
Cursor  
You can press 6, 9, 7, or 8 to move the cursor around the  
graph. When you first display the graph, no cursor is visible.  
As soon as you press 6, 9, 7, or 8, the cursor moves from  
the center of the viewing window.  
As you move the cursor around the graph, the values of the  
variables X and Y are updated, and the coordinate values of  
the cursor location are displayed at the bottom of the screen.  
Coordinate values generally appear in floating-decimal format.  
The numeric display settings on the MODE screen do not  
affect coordinate display.  
To see the graph without the cursor or coordinate values,  
press , or M. When you press 6, 9, 7, or 8, the  
cursor begins to move from the same position.  
Graphing  
Accuracy  
The free-moving cursor moves from dot to dot on the screen.  
When you move the cursor to a dot that appears to be “on” the  
function, it may be near, but not on, the function; therefore,  
the coordinate value displayed at the bottom of the screen is  
not necessarily a point on the function. To move the cursor  
along a function, use TRACE (page 4-13).  
The displayed coordinate values of the free-moving cursor  
approximate actual math coordinates accurate to within the  
width/height of the dot. As XMIN and XMAX (and YMIN and  
YMAX) get closer together (after a ZOOM IN, for example),  
graphing accuracy increases, and the coordinate values more  
closely represent the math coordinates.  
) Free-moving cursor “on” the curve  
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Exploring a Graph with TRACE  
TRACE moves the cursor from one plotted point to the next along a function.  
The cursor coordinates are displayed at the bottom of the screen.  
Beginning a  
Trace  
Press + to begin a trace. If the graph is not displayed  
already, the TI-80 displays it. The cursor is on the first  
selected function in the Y= list at the middle X value on the  
screen. The number of the function appears at the upper right  
of the display.  
Note: If any STAT PLOTS are turned on, the TI-80 attempts to  
trace the first stat plot.  
Moving along a  
Function  
Press 9 and 6 to move the cursor along the function. Each  
press moves the cursor from one plotted point to the next.  
Press 2 9 and 2 6 to move the cursor five plotted points  
at a time. Tracing updates and displays the values of the  
variables X and Y. The Y value is calculated from the X value;  
that is, Y=Yn(X). If the function is undefined at an X value, the  
Y value is blank.  
)
Trace cursor on the curve.  
If the Y value of a function is above or below the viewing  
window, the cursor disappears as you move it to that portion  
of the function. However, the coordinate values at the bottom  
of the screen indicate the cursor coordinates.  
Panning to the  
Left or Right  
If you trace a function off the left or right edge of the screen,  
the viewing window automatically pans to the right or left.  
XMIN and XMAX are updated to correspond to the new  
viewing window.  
Note: The screen does not pan if a STAT PLOT is on.  
QuickZoom  
While tracing, you can press ¸ to adjust the viewing  
window so that the cursor location becomes the center of a  
new viewing window, even if the cursor is above or below the  
display. This allows “panning” up and down. After  
QuickZoom, TRACE is still active.  
Function Graphing 4-13  
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Moving from  
Function to  
Function  
To trace another selected function on the graph, press 8 or 7  
to move the cursor to that function. The cursor moves to the  
new function at the same X value. The function number in the  
upper right corner of the display changes.  
The cursor movement is based on the order of the selected  
functions in the Y= list, not the appearance of the functions as  
graphed on the screen.  
Leaving TRACE  
To leave TRACE:  
¦
¦
¦
Select another screen by pressing the appropriate key,  
such as ) or *.  
Press , or M to see the graph without the Trace  
cursor.  
Press 2 . to return to the Home screen.  
The Trace cursor remains in the same location if you leave  
TRACE and return, as long as Smart Graph has not caused the  
graph to be replotted.  
Using TRACE in  
a Program  
On a blank line in the program editor, press +. The  
instruction Trace is copied to the cursor location. When the  
instruction is encountered during program execution, the  
graph is displayed with the Trace cursor on the first selected  
function. As you trace, the cursor coordinate values are  
updated. When you finish tracing the function(s), press ¸  
to resume program execution.  
4-14 Function Graphing  
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Exploring a Graph with ZOOM  
Pressing * displays a menu that allows you to adjust the viewing window of  
the graph quickly in a variety of ways. All of the Zoom instructions are  
accessible from programs.  
ZOOM  
Menu  
ZOOM  
1:ZBOX  
2:ZOOM IN  
Draws box to define viewing window.  
Magnifies graph around cursor.  
3:ZOOM OUT Views more of graph around cursor.  
4:ZDECIMAL Sets .1 as dot size.  
5:ZSQUARE  
6:ZSTANDARD Sets standard Window variables.  
7:ZTRIG Sets built-in trig Window variables.  
Sets equal sized-dots on X and Y axes.  
ZBOX  
ZBOX lets you use the cursor to select opposite corners of a  
box to define a new viewing window.  
1. Select ZBOX from the ZOOM menu. The different cursor at  
the center of the screen indicates that you are using a  
Zoom instruction.  
2. Move the cursor to any corner of the box you want to  
define, and then press ¸. As you move the cursor  
away from the point just selected, you see a small square  
dot, indicating that the first corner is selected.  
3. Move the cursor to the diagonal corner of the box you  
want to define. As you move the cursor, the boundaries of  
the box change on the screen.  
Note: Before you press ¸, you  
can cancel ZBOX at any time by  
pressing M.  
4. When the box is defined as you want it, press ¸ to  
replot the graph.  
You can repeat steps 2 through 4 to do another ZBOX.  
Function Graphing 4-15  
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ZOOM IN  
ZOOM OUT  
ZOOM IN magnifies the graph around the cursor location. The  
XFACT and YFACT settings determine the extent of the zoom  
(page 4-18). The default value for both XFACT and YFACT is  
4.  
1. After checking or changing XFACT and YFACT, select  
ZOOM IN from the ZOOM menu.  
Notice the different cursor. It indicates that you are using  
a Zoom instruction.  
2. Move the cursor to the point that you want as the center of  
the new viewing window, and then press ¸.  
The TI-80 adjusts the viewing window by XFACT and  
YFACT, updates the Window variables, and replots the  
selected functions centered on the cursor location.  
3. ZOOM IN is still turned on. To zoom in on the graph again:  
¦
¦
At the same point, press ¸.  
At a new point, move the cursor to the point that you  
want as the center of the new viewing window, and then  
press ¸.  
ZOOM OUT displays a greater portion of the graph, centered  
on the cursor location, to provide a more global view. The  
procedure for ZOOM OUT is the same as for ZOOM IN.  
Leaving ZOOM  
To leave ZOOM IN or ZOOM OUT:  
IN or ZOOM OUT  
¦
Select another screen by pressing the appropriate key,  
such as + or ,.  
¦
Press 2 . to return to the Home screen.  
4-16 Function Graphing  
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ZDECIMAL  
ZDECIMAL replots the functions immediately, updates the  
Window variables to preset values that set @X and @Y equal to  
.1, and defines the X and Y value of each pixel as one decimal.  
XMIN = L3.1  
XMAX = 3.1  
XSCL = 1  
YMIN = L2.3  
YMAX = 2.3  
YSCL = 1  
ZSQUARE  
ZSTANDARD  
ZTRIG  
ZSQUARE replots the functions immediately, redefining the  
window based on the current Window variables, but adjusted  
in only one direction so that @X=@Y. This makes the graph of a  
circle look like a circle. XSCL and YSCL remain unchanged.  
The midpoint of the current graph (not the intersection of the  
axes) becomes the midpoint of the new graph.  
ZSTANDARD replots the functions immediately, updating the  
Window variables to the standard values:  
XMIN = L10  
XMAX = 10  
XSCL = 1  
YMIN = L10  
YMAX = 10  
YSCL = 1  
ZTRIG replots the functions immediately, updating the  
Window variables to preset values appropriate for plotting trig  
functions. In RADIAN mode, these are:  
XMIN = L(31/12)p (L8.115781..)  
XMAX = (31/12)p (8.1157810..)  
XSCL = (p/2) (1.5707963..)  
YMIN = L2 (L2)  
YMAX = 2 (2)  
YSCL = 1 (1)  
Function Graphing 4-17  
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Setting the Zoom Factors  
The Zoom factors, XFACT and YFACT, determine the extent of the change for the  
viewing window created by ZOOM IN or ZOOM OUT on a graph.  
Zoom Factors  
Zoom factors are positive numbers (not necessarily integers)  
greater than or equal to 1. They define the magnification or  
reduction factor used to ZOOM IN or ZOOM OUT around a  
point.  
Checking Zoom  
Factors  
To review the current values of the Zoom factors (XFACT and  
YFACT):  
1. Press L, and then press 1 to select WINDOW....  
2. Press 9 to select XFACT or 0 to select YFACT. XFACT or  
YFACT is copied to the cursor location.  
3. Press ¸. The Zoom factor is displayed.  
Setting Zoom  
To set the Zoom factors XFACT and YFACT from the Home  
Factors from the screen or a program, begin on a blank line.  
Home Screen or  
a Program  
1. Enter the factor, and then press §.  
2. Press L, and then press 1 to select WINDOW....  
3. Press 9 to select XFACT or 0 to select YFACT. XFACT or  
YFACT is copied to the cursor location on the Home  
screen.  
4. Press ¸ to store the Zoom factor to the variable.  
4-18 Function Graphing  
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Chapter 5: Parametric Graphing  
This chapter describes how to graph parametric equations on the TI.80. Before  
doing parametric graphing, you should be familiar with Chapter 4, Function  
Graphing.  
Chapter  
Contents  
Getting Started: Path of a Ball ......................  
Defining and Displaying a Parametric Graph..........  
Exploring a Parametric Graph ......................  
5-2  
5-3  
5-6  
Parametric Graphing 5-1  
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Getting Started: Path of a Ball  
Getting Started is a fast-paced introduction. Read the chapter for details.  
Graph the parametric equation that describes the path of a ball kicked at an  
angle of 60¡ with an initial velocity of 15 meters per second. (Ignore air  
resistance.) What is the maximum height? When does the ball strike the ground?  
1. Press 3, and then press 8 8 8 8 8 9 ¸ to  
select PARAM mode.  
For initial velocity v0 and angle q, the horizontal  
component of the ball as a function of time is  
X(t) = t v0 cos q. The vertical component is  
Y(t) = t v0 sin q -(gà2) t2. The gravity constant g is  
9.8 màsec2.  
2. Press (. Press 15 @ X 60 2 E 1 (to select  
¡) ¸ to define the X portion of the parametric  
equation in terms of T.  
3. Press 15 @ W 60 2 E 1 (to select ¡) | c  
9.8 e 2 d @ a ¸ to define the Y portion.  
4. Press ). Enter the Window variables  
appropriate for this problem.  
TMIN=0  
TMAX=3  
TSTEP=.2  
XMIN=ë2  
XMAX=25  
XSCL=5  
YMIN=ë2  
YMAX=10  
YSCL=5  
5. Press + to graph the position of the ball as a  
function of time.  
Tracing begins at TMIN. As you press 9~ to trace the  
curve, the cursor follows the path of the ball over  
time. The values for X (distance), Y (height), and T  
(time) are displayed at the bottom of the screen.  
The maximum height is approximately 8.6 meters. The  
ball strikes the ground in approximately 2.6 seconds.  
5-2 Parametric Graphing  
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Defining and Displaying a Parametric Graph  
Parametric equations consist of an X component and a Y component, each  
expressed in terms of the same independent variable T. They are often used to  
graph equations over time. Up to three pairs of parametric equations can be  
defined and graphed at a time.  
Defining a  
Parametric  
Graph  
The steps for defining a parametric graph are the same as  
those for defining a function graph (page 4-3). Differences are  
noted below.  
Setting  
Parametric  
Graph Modes  
Press 3 to display the mode settings. To graph parametric  
equations, you must select PARAM before you enter Window  
variables or enter the components of parametric equations.  
Normally, you should also select CONNECTED to obtain a  
more meaningful parametric graph.  
Displaying  
Parametric  
Equations  
After selecting PARAM mode, press ( to display the  
parametric Y= edit screen.  
On this screen, you display and enter both the X and Y  
components. The TI-80 allows three parametric equations,  
each defined in terms of T.  
Defining  
Parametric  
Equations  
Follow the same procedures as for function graphing (pages  
4-5 to 4-6) to enter the two components that define a new  
parametric equation.  
¦
¦
You must define both the X and Y components in a pair.  
The independent variable in each component is T. You  
may press @, rather than pressing ? ãTä, to enter the  
parametric variable T. (PARAM mode defines the  
independent variable as T.)  
Parametric Graphing 5-3  
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Selecting  
Parametric  
Equations  
The TI-80 graphs only the parametric equations you select.  
The highlighted = sign on both components of an equation  
indicates that the equation is selected.  
You may select any or all of the equations on the parametric  
Y= edit screen.  
To change the selection status of a parametric equation, press  
6 to move the cursor onto the = sign of either the X or Y  
component and press ¸. The status on both the X and Y  
components changes.  
Note: When you enter both components of an equation or edit  
either component, that equation is selected automatically.  
Setting Window  
Variables  
Press ) to display the current Window variable values.  
The Window variables define the viewing window. The values  
shown are the standard values in RADIAN mode.  
TMIN=0  
Smallest T value to evaluate.  
Largest T value to evaluate.  
TMAX=6.283185307  
TSTEP=.1308996938996 T value increment.  
XMIN=L10  
XMAX=10  
XSCL=1  
Smallest X value to be displayed.  
Largest X value to be displayed.  
Spacing between X tick marks.  
Smallest Y value to be displayed.  
Largest Y value to be displayed.  
Spacing between Y tick marks.  
YMIN=L10  
YMAX=10  
YSCL=1  
To change a Window variable value, follow the steps given for  
function graphing (page 4-8).  
Note: You may want to change the T variable values to ensure  
that sufficient points are plotted.  
5-4 Parametric Graphing  
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Displaying a  
Graph  
When you press ,, the TI-80 plots the selected  
parametric equations. It evaluates both the X and the Y  
component for each value of T (from TMIN to TMAX in  
intervals of TSTEP) and then plots each point defined by X  
and Y. The Window variables define the viewing window.  
As a graph is plotted, the TI-80 updates X, Y, and T.  
Note: Smart Graph applies to parametric graphs also (page  
4-11).  
VARS WINDOW  
and Y-VARS  
Menus  
By means of the VARS WINDOW... and Y-VARS menus, you  
can:  
¦
Access functions by using the name of the component of  
the equation as a variable.  
¦
Select or deselect parametric equations from a program,  
using the FNON and FNOFF commands (page 4-8).  
¦
¦
Store parametric equations.  
Store values directly to Window variables.  
Parametric Graphing 5-5  
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Exploring a Parametric Graph  
As in function graphing, three tools are available for exploring a graph: the free-  
moving cursor, tracing, and zooming.  
Free-Moving  
Cursor  
The free-moving cursor works the same in parametric  
graphing as in function graphing (page 4-12).  
Tracing a  
Parametric  
Graph  
Pressing + puts the Trace cursor on the first selected  
equation, at TMIN. You can then trace along the equation.  
6 or 9  
Moves the cursor one TSTEP at a time.  
2 6 or 9 ~  
7 or 8  
Moves the cursor five TSTEPs at a time.  
Changes to the previous or next equation.  
The equation number shows in the upper  
right of the display.  
M
Cancels tracing.  
For each value of T, the calculator displays values for X and Y.  
The values for X, Y, and T are updated as you move the Trace  
cursor. If the cursor moves off the top or bottom of the  
screen, the coordinate values continue to change  
appropriately.  
The Trace cursor remains in the same location if you leave  
TRACE and return, unless Smart Graph replots the graph.  
QuickZoom is available in parametric graphing, but panning is  
not (page 4-13).  
Zooming in on a  
Parametric  
Graph  
Pressing * works the same in parametric graphing as in  
function graphing (page 4-15).  
Parametric graphing uses the additional Window variables  
TMIN, TMAX, and TSTEP. These variables are not affected by  
zooming unless you select ZSTANDARD, where TMIN = 0,  
TMAX = 6.283185307 (2p), and TSTEP = .1308996938996  
(p/24).  
5-6 Parametric Graphing  
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Chapter 6: Tables  
This chapter describes how to use tables on the TI.80. A table evaluates the  
selected functions from the Y= list and displays each value for the independent  
variable along with the evaluated value for each corresponding dependent  
variable.  
Chapter  
Contents  
Getting Started: Roots of a Function.................  
Defining the Independent Variable ..................  
Defining the Dependent Variable ....................  
Displaying the Table...............................  
6-2  
6-3  
6-4  
6-5  
Tables 6-1  
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Getting Started: Roots of a Function  
Getting Started is a fast-paced introduction. Read the chapter for details.  
2
Evaluate the function Y=X – 4X+3 at each integer between L10 and 10. How  
many sign changes are there, and where do they occur?  
1. If necessary, select FUNC from the MODE menu.  
Press 2 # to display the TABLE SETUP  
screen. Press · 10 to set TBLMIN=L10. Leave  
@TBL=1.  
2. Press ( @ a | 4 @ « 3 to enter the function  
Y1=X2 – 4X+3.  
3. Press 2 & to display the table screen.  
4. Press 8 repeatedly to view the changes in the value  
of Y1.  
6-2 Tables  
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Defining the Independent Variable  
The independent variable for a table is the independent variable in the current  
graphing mode (X for FUNC mode and T for PARAM mode). You define the  
minimum value and the incremental value for the independent variable on the  
TABLE SETUP screen.  
TABLE SETUP  
Screen  
To display the TABLE SETUP screen, press 2 #. The  
default values are shown below.  
TBLMIN and  
TBLMIN (table minimum) defines the initial value for the  
@TBL  
independent variable: X (FUNC mode) or T (PARAM mode).  
@TBL (table step) defines the increment for the independent  
variable.  
To change TBLMIN and @TBL, simply enter the values at the  
blinking cursor. To move between TBLMIN and @TBL, press 8  
and 7.  
Setting Up a  
Table from the  
Home Screen or  
a Program  
You can also store values to TBLMIN and @TBL from the  
Home screen or a program. The variable names are on the  
VARS TABLE... menu.  
To change TBLMIN or @TBL from the Home screen or a  
program, begin on a blank line.  
1. Enter the value for TBLMIN or @TBL.  
2. Press §.  
3. Press L to display the VARS menu.  
4. Press 3 to select TABLE....  
5. Select the table variable (TBLMIN or @TBL). The name of  
the variable is copied to the cursor location.  
6. Press ¸ to store the value for the table variable.  
Tables 6-3  
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Defining the Dependent Variable  
The selected functions from the Y= list define the dependent variables. You can  
have as many dependent variables as there are functions in the current graphing  
mode (four for FUNC mode and six for PARAM mode).  
From the Y=  
Editor  
Enter the functions to define the dependent variables in the  
Y= editor.  
FUNC Mode  
PARAM Mode  
In PARAM mode, you must define both components of the  
parametric equation (Chapter 5).  
Only functions that are selected are displayed in the table.  
(When = is highlighted, the function is selected.) You can  
select and deselect functions from the Y= list, from the Home  
screen, or from a program. (Refer to page 4-8 for information  
on selecting and deselecting.)  
6-4 Tables  
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Displaying the Table  
The table displays up to six values for the independent variable, along with the  
six corresponding values of one dependent variable, at a time. Once the table is  
displayed, you can press 6, 7, 9, and 8 to move around and scroll the table,  
displaying other independent and dependent values.  
The Table  
Press 2 & to display the table screen.  
FUNC Mode PARAM Mode  
The top line displays the name of the independent variable (X  
for FUNC mode; T for PARAM mode) and one dependent  
variable (Yn for FUNC mode; XnT or YnT for PARAM mode).  
The bottom line displays the full value of the current cell,  
which is indicated by the rectangular cursor. The center  
portion is used to display the values of the variables,  
abbreviated to six digits if necessary.  
Displaying More  
Independent  
Values  
Press 7 and 8 to display additional values for the  
independent variable and the values for one corresponding  
dependent variable.  
Note: You can scroll “back” from the value entered for  
TBLMIN. As you scroll, TBLMIN is updated automatically to  
the value shown on the top line of the table. In the example  
below, TBLMIN=0, @TBL=1, and Y1=Xñ+2 generates and  
displays values of X=0, . . ., 5. You can press 7 to scroll  
backward and display the table for X=1, . . . ,4.  
Tables 6-5  
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Displaying Other If you have more than one function defined and selected,  
Dependent  
Variables  
press 9 to display other dependent variables. In the example  
below, TBLMIN=0, @TBL=1, Y1=X2+2 and Y2=X3–2. You can  
press 9 9 to see the values for Y2.  
6-6 Tables  
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Chapter 7: Draw Operations  
This chapter describes how to use the DRAW operations of the TI.80. Before  
using the DRAW operations, you should be familiar with Chapter 4, Function  
Graphing.  
Chapter  
Contents  
Getting Started: Shading a Graph....................  
DRAW DRAW Menu ...............................  
Drawing Lines ....................................  
Drawing Horizontal and Vertical Lines ...............  
Drawing a Function ...............................  
Shading Areas on a Graph ..........................  
7-2  
7-3  
7-4  
7-5  
7-6  
7-7  
Drawing Points ................................... 7-10  
Clearing a Drawing................................ 7-12  
Draw Operations 7-1  
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Getting Started: Shading a Graph  
Getting Started is a fast-paced introduction. Read the chapter for details.  
ä
Shade the area below the function Y=X N2 and above the functions Y=X+1 and  
-
Y= X.  
1. If necessary, select FUNC mode. Press ( and enter  
the functions:  
Y1= @ a | 2 ¸  
Y2= @ « 1 ¸  
Y3= · @ ¸  
(Be sure that Y4 is cleared or turned off.)  
2. Press * 4 to select the ZDECIMAL viewing  
window, clear any existing drawings, and display the  
viewing window and graph.  
3. Press 2 . to return to the Home screen.  
4. Press 2 F 7 to select SHADE_Y<, which is  
copied to the Home screen.  
5. Press 2 G 1 (to select Y1).  
6. Press 2 ° to add another instruction to this line.  
7. Press 2 F 6 to select SHADE_Y>, which is  
copied to the Home screen.  
8. Press 2 G 2 (to select Y2) b 2 G 3 (to  
select Y3).  
9. Press ¸ to see the functions and shading on the  
graph.  
7-2 Draw Operations  
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DRAW DRAW Menu  
To display the DRAW DRAW menu, press 2 F. What happens when you  
select an item from this menu depends on whether or not a graph is displayed  
when you access the menu, as described under each operation.  
DRAW DRAW  
Menu  
DRAW POINTS  
1:CLRDRAW  
2:LINE(  
Clears all drawn elements.  
Draws a line between two points.  
3:HORIZONTAL Draws a horizontal line.  
4:VERTICAL  
5:DRAWF  
6:SHADE_Y>  
7:SHADE_Y<  
8:SHADE(  
Draws a vertical line.  
Draws a function.  
Shades an area.  
Shades an area.  
Shades an area.  
9:GRIDON  
0:GRIDOFF  
Turns the graph grid on.  
Turns the graph grid off.  
(See page 7-12 for an explanation of CLRDRAW.)  
Before Drawing  
on a Graph  
Because Draw operations draw on top of the graph of  
currently selected functions, you may want to do one or more  
of the following before drawing on a graph:  
¦
¦
¦
¦
¦
¦
Change the mode settings.  
Enter or edit functions in the Y= list.  
Select or deselect functions in the Y= list.  
Change Window variable values.  
Turn STAT PLOTS on or off.  
Clear existing drawings with CLRDRAW (page 7-12).  
Drawing on a  
Graph  
Draw operations can draw on FUNC and PARAM graphs. The  
coordinates for all Draw instructions are always the  
X-coordinate and Y-coordinate values of the display.  
You can use most of the operations from the DRAW DRAW  
and DRAW POINTS menus to draw directly on a graph, using  
the cursor to identify coordinates; or you can execute these  
instructions from the Home screen or a program.  
Draw Operations 7-3  
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Drawing Lines  
While a graph is displayed, LINE( lets you use the cursor to define a line on the  
graph. If a graph is not displayed, the instruction is copied to the Home screen.  
Directly on a  
Graph  
To define a line directly on a graph:  
1. When a graph is displayed, select LINE( from the  
DRAW DRAW menu (item 2).  
2. Position the cursor at the beginning point of the line you  
want to draw. Press ¸.  
3. Move the cursor to the end point of the line you want to  
draw. The line is displayed as you move the cursor. Press  
¸.  
To continue to draw lines, repeat steps 2 and 3. To cancel  
LINE(, press M.  
From the Home  
Screen or a  
Program  
LINE( (DRAW DRAW, item 2) draws a line between the  
coordinates (X1,Y1) and (X2,Y2). The values may be entered  
as expressions.  
LINE(X1,Y1,X2,Y2)  
For example, enter LINE(0,0,6,9) on the Home screen, and  
then press ¸.  
7-4 Draw Operations  
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Drawing Horizontal and Vertical Lines  
While a graph is displayed, HORIZONTAL and VERTICAL let you define lines on  
the graph using the cursor. If a graph is not displayed, the instruction is copied  
to the Home screen.  
Directly on a  
Graph  
To draw horizontal and vertical lines directly on a graph:  
1. When a graph is displayed, select HORIZONTAL (item 3)  
or VERTICAL (item 4) from the DRAW DRAW menu.  
2. A line is displayed that moves as you move the cursor.  
Position the cursor where you want to draw the line. Press  
¸. The line is drawn on the graph.  
To continue to draw lines, repeat step 2. To cancel  
HORIZONTAL or VERTICAL, press M.  
From the Home  
Screen or a  
Program  
HORIZONTAL (DRAW DRAW, item 3) draws a horizontal line  
at Y=Y (which can be an expression, but not a list).  
HORIZONTAL Y  
VERTICAL (DRAW DRAW, item 4) draws a vertical line at  
X=X (which can be an expression, but not a list).  
VERTICAL X  
Note: In the example above, the horizontal line is drawn first,  
and then the vertical line is drawn.  
Draw Operations 7-5  
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Drawing a Function  
DRAWF (draw function) draws a function on the current graph. DRAWF must be  
entered on the Home screen or in the program editor.  
Drawing a  
Function  
DRAWF (draw function, DRAW DRAW, item 5) is not an  
interactive operation. It draws the specified expression as a  
function in terms of X on the current graph.  
DRAWF expression  
For example, if Y1=.2Xò–2X+6 is the only selected function,  
DRAWF Y1–5 plots Y1 and then draws the function Y1–5  
when you press ¸.  
Note: You cannot trace on DRAWF functions.  
Using GRIDON  
and GRIDOFF  
GRIDON (DRAW DRAW, item 9) and GRIDOFF  
(DRAW DRAW, item 0) set graphs to be drawn with the grid  
points on or off, respectively. The grid points correspond to  
the axes tick marks. The default for the TI-80 is GRIDOFF.  
1. From the Home screen, press 2 F to display the  
DRAW menu.  
2. Press 9 to select GRIDON, or press 0 to select GRIDOFF.  
3. Press ¸. The message DONE is displayed. The next  
time the graph is displayed, the grid points will be on if  
you selected GRIDON, or off if you selected GRIDOFF.  
7-6 Draw Operations  
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Shading Areas on a Graph  
There are three shading instructions on the DRAW DRAW menu: SHADE_Y>,  
SHADE_Y<, and SHADE(. These instructions are not interactive; they must be  
entered on the Home screen or in the program editor.  
Shading Areas  
SHADE_Y> (DRAW DRAW, item 6) takes up to four  
above a Function arguments (functions of X).  
SHADE_Y>function  
SHADE_Y>function1, . . . ,function4  
When executed, SHADE_Y> plots the specified function(s) on  
the graph and shades the area above the function with a  
pattern.  
The patterns for shading are automatically assigned in the  
following order.  
Function 1  
Function 2  
Function 3  
Function 4  
Vertical pattern.  
Diagonal pattern, lower left to upper right.  
Diagonal pattern, upper left to lower right.  
Horizontal pattern.  
When you specify multiple functions, the shading is done  
sequentially.  
Draw Operations 7-7  
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Shading Areas  
SHADE_Y< (DRAW DRAW, item 7) takes up to four  
below a Function arguments (functions of X).  
SHADE_Y<function  
SHADE_Y<function1, . . . ,function4  
When executed, SHADE_Y< plots the specified function(s) on  
the graph and shades the area below the function with a  
pattern.  
The patterns for shading are automatically assigned in the  
following order.  
Function 1  
Function 2  
Function 3  
Function 4  
Horizontal pattern.  
Diagonal pattern, upper left to lower right.  
Diagonal pattern, lower left to upper right.  
Vertical pattern.  
Note that the patterns are assigned in reverse order from the  
SHADE_Y> patterns.  
When you specify multiple functions, the shading is done  
sequentially.  
7-8 Draw Operations  
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Shading a Graph SHADE( (DRAW DRAW, item 8) shades the area on a graph  
that is below one specified function and above another,  
between two X values. SHADE( is not an interactive operation.  
It draws lowerfunc and upperfunc in terms of X on the  
current graph and shades the area that is specifically above  
lowerfunc and below upperfunc. Only the areas where  
lowerfunc < upperfunc are shaded.  
You can specify the shading resolution (an integer between 1  
and 9). If none is specified, 1 is used. resolution=1 shades  
every pixel. resolution=2 shades every second pixel.  
resolution=3 shades every third pixel, and so on.  
Optionally, you can specify Xleft (the left boundary) and  
Xright (the right boundary) for the shaded area. If Xleft or  
Xright is not specified, XMIN and XMAX are used.  
SHADE(lowerfunc,upperfunc)  
SHADE(lowerfunc,upperfunc,resolution)  
SHADE(lowerfunc,upperfunc,resolution,Xleft)  
SHADE(lowerfunc,upperfunc,resolution,Xleft,Xright)  
Draw Operations 7-9  
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Drawing Points  
To display the DRAW POINTS menu, press 2 F 9. What happens when  
you select an item from this menu depends on whether or not a graph is  
displayed when you access the menu, as described under each operation.  
DRAW POINTS  
Menu  
DRAW POINTS  
1:PT-ON(  
2:PT-OFF(  
Turn on a point.  
Turn off a point.  
3:PT-CHANGE( Toggle a point on or off.  
Drawing a Point  
Directly on a  
Graph  
To draw points directly on a graph:  
1. When a graph is displayed, select PT.ON( from the  
DRAW POINTS menu (item 1).  
2. Position the cursor at the location on the display where  
you want to draw the point. Press ¸. The point is  
drawn.  
To continue to draw points, repeat step 2. To cancel PT.ON(,  
press M.  
7-10 Draw Operations  
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PT.OFF(  
PT.CHANGE(  
Procedures for using PT.OFF( (point off, DRAW POINTS, item  
2) to turn off (erase) a point and PT.CHANGE( (point change,  
DRAW POINTS, item 3) to toggle (reverse) a point on and off  
are the same as for PT.ON(.  
From the Home  
Screen or a  
Program  
When you use these instructions from the Home screen or a  
program, you must specify the X-coordinate and the  
Y-coordinate of the point as arguments for the instructions.  
PT.ON( turns on the point at (X=X,Y=Y). PT.OFF( turns the  
point off, and PT.CHANGE( toggles the point between on and  
off.  
PT.ON(X,Y)  
PT.OFF(X,Y)  
PT.CHANGE(X,Y)  
Draw Operations 7-11  
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Clearing a Drawing  
All points, lines, and shading drawn on a graph with DRAW operations are  
temporary. They remain only until you execute a CLRDRAW (clear drawing)  
instruction or a change prompts Smart Graph to replot the graph, at which time  
all drawn elements are erased.  
When a Graph Is To clear drawings from the currently displayed graph, select  
Displayed  
CLRDRAW from the DRAW DRAW menu (item 1). The current  
graph is plotted and displayed immediately with no drawn  
elements.  
Note that CLRDRAW gives you a quick way to replot the  
current graph, in addition to clearing the current drawings.  
From the Home  
Screen or a  
Program  
Begin on a blank line on the Home screen or in the program  
editor. Select CLRDRAW from the DRAW DRAW menu (item  
1). The instruction is copied to the cursor location.  
When the instruction is executed, it clears all drawings from  
the current graph and displays the message DONE. The next  
time you display the graph, all drawn points, lines, and shaded  
areas will be gone.  
7-12 Draw Operations  
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Chapter 8: Lists  
This chapter describes the list features of the TI-80. The TI.80 can store up to six  
lists. A list, depending on available memory, can have up to 99 elements.  
Chapter  
Contents  
Getting Started: Generating a Sequence ..............  
About Lists.......................................  
LIST OPS Operations..............................  
LIST MATH Operations ............................  
8-2  
8-3  
8-6  
8-9  
Lists 8-1  
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Getting Started: Generating a Sequence  
Getting Started is a fast-paced introduction. Read the chapter for details.  
ñ
Calculate the first eight terms of the sequence 1àA and display them in fraction  
form.  
The SEQ( function returns a list of values based on five arguments: an expression,  
a variable to be incremented, a beginning value, an ending value, and an increment.  
For this example, the beginning value is 1, the ending value is 8, and the increment  
is 1.  
1. Begin on a blank line on the Home screen. Press 2  
= to display the LIST OPS menu.  
2. Press 4 to select SEQ(. The function name is copied  
to the cursor location on the Home screen.  
3. Press 1 e ? A a b ? A b 1 b 8 b 1 d  
§ 2 ¢. Press ¸ to generate the list and  
store it in L1. The list is displayed on the Home  
screen.  
4. Use 9 to scroll the list to see all of the elements.  
5. Press J 4 (to select 4FRAC). On the Home screen,  
ANS is typed automatically, followed by 4FRAC.  
6. Press ¸ to show the sequence in fraction form.  
Use 9 to scroll the list to see all of the elements.  
8-2 Lists  
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About Lists  
The TI-80 has six list variables: L1, L2, L3, L4, L5, and L6. On the Home screen or  
in a program, you can use, enter, store, and display lists. The list names are on  
the keyboard. A list may have a maximum of 99 elements.  
Using a List in  
an Expression  
To use a list in an expression, you may:  
¦
Use the name of the list (L1, L2, L3, L4, L5, or L6) in the  
expression.  
¦
Enter the list directly in the expression.  
Entering a List in 1. Press 2 [to indicate the beginning of the list.  
an Expression  
2. Enter a value (which can be an expression) for each  
element in the list, separated by commas.  
3. Press 2 \ to indicate the end of the list.  
The expression is evaluated when the entry is executed.  
Commas are required on entry to separate elements, but they  
are not displayed on output.  
Saving a List in  
Memory  
You can save a list in memory in two ways:  
¦
¦
Enter the list in the STAT list editor (Chapter 9).  
Enter the list on a blank line on the Home screen or in a  
program, press §, and then enter the name of the list  
(L1, L2, L3, L4, L5, or L6).  
Copying One  
To copy a list, store it to another list.  
List to Another  
Lists 8-3  
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Displaying a List To display the contents of a list on the Home screen, enter the  
on the Home  
name of the list, and press ¸.  
Screen  
A open brace ({)without a corresponding close brace (})  
indicates that a list is too long to be displayed in its entirety.  
Press 9 and 6 to display the rest of the list.  
Storing to or  
Recalling a List  
Element  
You can store a value to or recall a value from a specific list  
element. Enter the name of the list, followed by the number of  
the element in parentheses. You can store to any element  
within the currently defined list dimensions or one beyond.  
listname(element)  
You can also edit a list by means of the STAT list editor  
(Chapter 9).  
Lists in Graphing You can use a list in a Y= expression. However, the list must  
be used in such a way that it resolves to a single value; for  
example, Y1=XSUM(1à(1.1^{1,2,3})).  
Note: Unlike the TI-82 and TI-85, you cannot use a list to  
graph a family of curves.  
8-4 Lists  
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Notes about  
Using Math  
Functions with  
Lists  
A list can be used to input several values for certain functions.  
(Other chapters and Appendix A state when a list is valid.)  
The function is evaluated for each element in the list, and a  
list is returned.  
¦
If a list is used with a function, the function must be valid  
for every element in the list.  
This returns an error because 1 is  
divided by 0.  
)
¦
If two lists are used with a two-argument function, the  
lengths of the lists must be the same. The answer is a list  
in which each element is calculated by evaluating the  
function using the corresponding elements in the lists.  
¦
If a list and a value are used with a two-argument function,  
the value is used with each element in the list.  
Lists 8-5  
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LIST OPS Operations  
Press 2 = to display the list operations on the LIST OPS menu.  
LIST OPS  
Menu  
OPS MATH  
1:SORTA(  
2:SORTD(  
3:DIM  
Sorts lists in ascending order.  
Sorts lists in descending order.  
Accesses the list dimension.  
Creates a sequence.  
4:SEQ(  
Note: SORTA( and SORTD( are the same as SORTA( and  
SORTD( on the STAT EDIT menu.  
SORTA(  
SORTD(  
SORTA( (sort ascending, LIST OPS, item 1) and SORTD( (sort  
descending, LIST OPS, item 2) have two uses.  
¦
With one list name, they sort the elements of an existing  
list and update the list in memory.  
¦
With two to six list names, they sort the first list and then  
sort the remaining lists as dependent lists, placing their  
elements in the same order as their corresponding  
elements in the first list. This allows you to keep sets of  
related data in the same order when you sort lists.  
All of the lists to be sorted must be the same length. The  
sorted lists are updated in memory.  
Note: You can reference a specific list only once in these  
instructions.  
SORTA(listname)  
SORTA(keylistname,dependlist1,dependlist2, . . .)  
SORTD(listname)  
SORTD(keylistname,dependlist1,dependlist2, . . .)  
*
8-6 Lists  
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Accessing List  
DIM (dimension, LIST OPS, item 3) returns the length (number  
Dimensions with of elements) of the specified list.  
DIM  
DIM list  
Creating a List  
with DIM  
DIM is used with § to create a new list with a specified  
number of elements. The elements of the new list are zeros.  
length!DIM listname  
Redimensioning  
a List with DIM  
DIM is also used with § to redimension an existing list.  
¦
¦
¦
The elements in the old list that are within the new  
dimension are not changed.  
Any elements in the old list that are outside the new  
dimension are eliminated.  
Any additional elements that are created are zeros.  
length!DIM listname  
Lists 8-7  
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SEQ(  
SEQ( (sequence, LIST OPS, item 4) requires five arguments:  
an expression, a variable to be incremented, a beginning  
value, an ending value, and an increment. SEQ( returns a list  
in which each element is the result of the evaluation of  
expression with regard to variable for values ranging from  
begin to end at steps of increment.  
SEQ(expression,variable,begin,end,increment)  
The variable need not be defined in memory. The increment  
can be negative.  
SEQ( can be used to generate a list of index numbers. This  
kind of list can be useful in data analysis.  
8-8 Lists  
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LIST MATH Operations  
Pressing 2 = 9 accesses the list math operations on the LIST MATH menu.  
LIST MATH  
Menu  
OPS MATH  
1:MIN(  
2:MAX(  
3:MEAN(  
Returns minimum element of a list.  
Returns maximum element of a list.  
Returns mean of a list.  
4:MEDIAN( Returns median of a list.  
5:SUM  
6:PROD  
Returns sum of all elements in a list.  
Returns product of all elements in a list.  
Note: MIN( and MAX( are the same as MIN( and MAX( on the  
MATH NUM menu.  
MIN(  
MAX(  
MIN( (minimum, LIST MATH, item 1) or MAX( (maximum,  
LIST MATH, item 2) returns the smallest or largest element of  
the specified list. If two lists are compared, it returns a list of  
the smaller or larger of each pair of elements in the two lists.  
MIN(list)  
MAX(list)  
MIN(listA,listB)  
MAX(listA,listB)  
MEAN(  
MEDIAN(  
MEAN( (LIST MATH, item 3) returns the mean value of the list.  
MEDIAN( (LIST MATH, item 4) returns the median value of the  
list.  
MEAN(list) or MEDIAN(list)  
If a second list is given, it is interpreted as the frequency of  
the elements in the list.  
MEAN(list,frequency) or MEDIAN(list,frequency)  
Lists 8-9  
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SUM  
SUM (summation, LIST MATH, item 5) returns the sum of the  
elements in the specified list.  
SUM list  
PROD  
PROD (product, LIST MATH, item 6) returns the product of  
the elements of the list.  
PROD list  
Sums and  
Products of  
Numeric  
You can combine SUM or PROD with SEQ( to obtain:  
upper  
expression(x)  
upper  
expression(x)  
Sequences  
G
x=lower  
x=lower  
To evaluate G 2(N–1) from N=1 to 4:  
8-10 Lists  
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Chapter 9: Statistics  
This chapter describes the tools for analyzing statistical data on the TI-80. These  
include entering lists of data, calculating statistical results, fitting data to a  
model, and plotting data.  
Chapter  
Contents  
Getting Started: Building Height and City Size.........  
Setting Up a Statistical Analysis.....................  
The STAT List Editor ..............................  
9-2  
9-8  
9-9  
Viewing, Entering, and Editing Lists ................. 9-10  
Sorting and Clearing Lists .......................... 9-13  
Statistical Analysis ................................ 9-14  
Types of Statistical Analysis ........................ 9-15  
Statistical Variables ............................... 9-17  
Statistical Plotting ................................ 9-18  
Statistical Analysis in a Program .................... 9-22  
Statistical Plotting in a Program..................... 9-23  
Statistics 9-1  
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Getting Started: Building Height and City Size  
Getting Started is a fast-paced introduction. Read the chapter for details.  
Determine a linear equation to fit the data below. Enter the data, and perform a  
linear regression. Then plot the data. Predict how many buildings of more than  
12 stories you would expect to find in a city of 300 thousand people.  
Population in Thousands  
Buildings > 12 Stories  
150  
500  
800  
250  
550  
750  
4
31  
42  
9
20  
55  
1. To clear any existing lists, press A 4 to copy  
CLRLIST to the Home screen.  
2. Press 2 ¢ b 2 £ b 2 ¤ b 2 t ¸.  
The message DONE is displayed.  
3. Press A 1 to display the STAT list editor. Enter  
150 to represent 150,000 for the population of the  
first city. As you type, the value is displayed on the  
bottom line.  
4. Press ¸. The value is shown in the first element  
of L1, and the cursor moves to the second element in  
the same list.  
9-2 Statistics  
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5. Enter the remaining elements of L1. Press:  
500 ¸.  
800 ¸.  
250 ¸.  
550 ¸.  
750 ¸.  
6. Press 9 to move to the first element of list L2.  
7. Enter the elements (number of buildings with more  
than 12 stories) of L2. Press:  
4 ¸.  
31 ¸.  
42 ¸.  
9 ¸.  
20 ¸.  
55 ¸.  
8. You can sort the data by size of city. Press 2 .  
M to return to a clear Home screen. Press A 2  
to select SORTA(, which is copied to the Home  
screen. Press 2 ¢ to select the independent list  
and then press b 2 £ to select the dependent list.  
Press d ¸. The message DONE is displayed. The  
lists have been updated in memory.  
9. Press A 1 to display the sorted lists in the STAT  
list editor.  
Statistics 9-3  
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After entering and sorting the data, define the STAT PLOTS and Window  
variables; then perform a linear regression (aX + b).  
10. Press y ¸ to display the STAT PLOTS screen.  
11. Press 1 to display the PLOT1 screen. Move the  
cursor to ON, if necessary, and press Í to turn  
PLOT1 on. Leave TYPE as scatter plot (¼), XL  
(independent list) as L1, YL (dependent list) as L2,  
and Mark as .  
12. Press ) to display the Window variables.  
Enter the following values.  
0 for XMIN  
1000 for XMAX  
100 for XSCL  
L15 for YMIN  
100 for YMAX  
10 for YSCL  
13. Press A 9 to display the STAT CALC menu.  
14. Press 3 to select LINREG(aX+b), which is copied to  
the Home screen. Press 2 ¢ b 2 £ ¸.  
The least-squares linear regression is calculated; the  
display shows the values for a (slope), b  
(y-intercept), and r (correlation coefficient).  
9-4 Statistics  
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Store the regression equation into the Y= list and graph it.  
15. In FUNC mode, press ( to display the Y= editor.  
Press M to clear Y1, if necessary. Turn off all  
other functions, if necessary.  
16. Press L to display the VARS menu.  
17. Press 2 to select STATISTICS..., and press 9 9 to  
display the VARS EQ menu.  
18. Press 5 to select REGEQ, which copies the linear  
regression to the Y= editor screen.  
Note: Each time you calculate a regression, the  
regression equation (REGEQ) is updated.  
19. Press ,. The data points are plotted (), and  
then the regression line is drawn.  
20. Press + and then ~ to trace the points in  
PLOT1, as indicated by P1 in the upper right corner  
of the display.  
Press to move to Y1, and continue tracing the  
function.  
Statistics 9-5  
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You can enter expressions to define lists in the STAT list editor. For example,  
you can now define predicted values and residuals (the differences between the  
observed values and the predicted values) for this problem.  
21. Press 1 to display the STAT list editor. Press  
~ ~ } to move the cursor onto the name L3.  
22. Press y ãY-VARSä 1 to select Y1, and then press £  
y ¢ ¤. This defines Lå as the values predicted  
by the LINREG line.  
23. Press Í to store the values in L3.  
24. To store the residuals in L4, press ~ } to move the  
cursor onto the name L4. To enter L4 = L2 N L3,  
press y £ (the observed) ¹ y ¤ (the  
predicted) Í.  
25. Press 2 ". Press 1 to select PLOT1. Move  
the cursor to OFF, and press Í to turn the plot  
off.  
26. Press 2 " 2 to select PLOT2. Move the  
cursor to ON and press Í to turn the plot on, if  
necessary. Press 8 8 Í to define XL as L1.  
Press 8 9 9 9 Í to define YL as L4. Press 8  
9 Í to set MARK as +.  
9-6 Statistics  
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Plot the residuals, and predict how many buildings of 12 or more stories there  
are in a city with a population of 300 thousand.  
27. Press ( 6 ¸ to turn off Y1.  
28. Press ), and change the Window variable  
values to best show the residuals. Use the minimum  
and maximum values of L4 (M10.31862745 and  
10.74019608) as guidelines for setting YMIN and  
YMAX.  
29. Press , to plot the residuals.  
+ marks each residual value.  
30. Press y ãQUITä M to return to a clear Home  
screen. Press y ãY-VARSä 1 to select Y1. Then  
press £ 300 d Í.  
The value of Y1 (the linear regression equation) for  
X=300 (which represents 300 thousand city  
population) is shown. Remember to round the  
number mentally to an integer (13) to represent  
whole buildings.  
Statistics 9-7  
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Setting Up a Statistical Analysis  
The data for statistical analyses is stored in lists. The TI.80 has six list variables  
(Lã through Lè) that you can use in STAT calculations. Several types of  
statistical analyses are available.  
Steps  
Follow these basic steps to perform statistical analyses.  
1. Enter the statistical data in lists (pages 9-9 through 9-13).  
2. Select the type of statistical calculations you want to do  
(pages 9-14 through 9-16), and specify the list names for  
the data.  
3. Calculate the statistical variables, or fit the data to a model  
(page 9-17).  
4. Plot the data (pages 9-18 through 9-21).  
9-8 Statistics  
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The STAT List Editor  
Pressing A accesses the STAT list editor and several instructions for use  
with lists (Lã through Lè). The instructions are discussed on page 9-13.  
STAT EDIT  
Menu  
EDIT CALC  
1:EDIT...  
2:SORTA(  
3:SORTD(  
Displays list editor.  
Sorts list in ascending order.  
Sorts list in descending order.  
4:CLRLIST Deletes all elements of list.  
Displaying the  
The STAT list editor gives you an easy environment in which  
STAT List Editor to enter or edit lists. You can also create lists directly from the  
keyboard (Chapter 8), if you prefer.  
To display the STAT list editor, press A and then press 1  
or ¸ to select EDIT... from the STAT EDIT menu.  
The top line of the STAT list editor displays the names of the  
lists (even if the list is empty). The center portion displays up  
to six elements of two lists, showing the values of the  
elements (abbreviated to six digits if necessary). The full  
value of the current element (indicated by the rectangular  
cursor) is shown on the bottom line.  
Entering List  
To enter a list into the STAT list editor:  
Elements in the  
STAT List Editor  
1. Display the STAT list editor.  
2. Enter the first value in the list, and press ¸ or 8. The  
value is entered, and the rectangular cursor moves down  
to the next position.  
3. Continue until you enter all the data in the list.  
Press 9 and 6 in the editor to move between lists.  
Note: You may enter an expression, which is evaluated when  
you press ¸, 8, or 7.  
Leaving the  
To leave the STAT list editor:  
STAT List Editor  
¦
¦
Select another screen by pressing the appropriate key.  
Press 2 . to return to the Home screen.  
Statistics 9-9  
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Viewing, Entering, and Editing Lists  
The STAT list editor has two “contexts,” viewing and editing. The current  
context determines the result of a key press. In both contexts, the full value of  
the highlighted element is displayed on the bottom line.  
Viewing Context  
In the viewing context, you can move quickly from one list  
element to the next.  
6 or 9  
Moves the rectangular cursor to the previous or  
next list.  
8 or 7  
Moves the rectangular cursor within the current  
column. On row 1, 7 moves the cursor to the list  
name.  
¸
M
Activates the edit cursor on the bottom line.  
Clears the value on the bottom line.  
Any entry  
character  
Clears the value on the bottom line; copies the  
character to the bottom line.  
2 /  
4
Inserts a list element (value is zero).  
Deletes the current list element and closes up the  
list.  
Editing  
Context  
In the editing context, an edit cursor is active on the bottom  
line; and you can change the value of the current list element.  
You can also move the cursor onto the list name and edit the  
entire list at once.  
6 or 9  
Moves the edit cursor within the value.  
8 or 7  
Stores the value on the bottom line to the list  
element; moves the rectangular cursor within the  
column. On row 1, 7 moves the cursor to the list  
name.  
¸
M
Stores the value on the bottom line to the list  
element; moves the rectangular cursor to the next  
element.  
Clears the value on the bottom line.  
Any entry  
character  
Copies the character to the edit-cursor location  
on the bottom line. If it is the first character  
typed, the value on the bottom line is cleared.  
2 /  
4
Activates the insert cursor.  
Deletes a character.  
9-10 Statistics  
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Deleting a List  
You can delete the contents of a list in several ways:  
¦
¦
¦
With the CLRLIST instruction (page 9-13).  
Through the MEMORY menu (Chapter 12).  
In the STAT list editor, by pressing 7 to move onto the list  
name and then pressing M ¸.  
¦
¦
In the STAT list editor, by deleting each element.  
On a command line, by entering 0!DIM listname.  
Editing a List  
Element  
To edit a list element:  
1. Display the STAT list editor.  
2. Move the rectangular cursor to the element you want to  
change.  
3. Press ¸ to switch to the editing context. Then:  
¦
¦
¦
Change the current value by inserting, deleting, or  
typing over digits.  
Press an entry key, such as a number or letter, to begin  
an entry. This automatically clears the value.  
Press M to clear the entire value and then enter a  
new value.  
Note: If you clear a value by mistake, you can  
immediately press ¸ to restore the value at the  
rectangular cursor.  
4. Press ¸ to store the new value and move to another  
element.  
Note: You may enter an expression, which is evaluated when  
you press ¸, 8, or 7.  
Statistics 9-11  
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You can enter or edit an entire list by moving the cursor to a list name on the top  
line of the STAT list editor and then pressing ¸. The bottom line displays  
Ln=Ln×1, if there is data already in the list. Type any expression that returns a  
list, and press ¸. The new list is displayed.  
Entering an  
Entire List  
To enter an entire list:  
1. Press A ¸. Enter several elements in L1.  
2. Press 7 and 9 as many times as necessary to move the  
cursor to the list name L2.  
3. Press 2 ¢ p 2. This is the expression that will define  
the elements in L2.  
4. Press ¸ to define and display L2.  
Editing an Entire To replace an existing list:  
List  
1. Move the cursor to the list name L2. L2=L2×1 is displayed.  
2. Enter a new expression to replace the existing values in  
L2, 2 ¢ p 3, for example. Then press ¸. The  
values in L2 are replaced, and the new values are  
displayed.  
9-12 Statistics  
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Sorting and Clearing Lists  
Items 2 through 4 on the STAT EDIT menu SORTA(, SORTD(, and CLRLIST let  
you sort or clear list data. Pressing A displays these instructions, and  
selecting an item copies the name of the instruction to the Home screen. Note  
that SORTA( and SORTD( are the same as SORTA( and SORTD( on the LIST OPS  
menu (Chapter 8).  
SORTA(  
SORTD(  
SORTA( (sort ascending, STAT EDIT, item 2) and SORTA(  
(sort descending, STAT EDIT, item 3) have two uses.  
¦
With one list name, they sort the elements of an existing  
list and update the list in memory.  
¦
With two to six list names, they sort the first list and then  
sort the remaining lists as dependent lists, placing their  
elements in the same order as their corresponding  
elements in the first list. This lets you sort two-variable  
data on X and keep the data pairs together.  
All of the lists to be sorted must be the same length. The  
sorted lists are updated in memory.  
Note: You can reference a specific list only once in these  
instructions.  
SORTA(listname)  
SORTA(keylistname,dependlistA,dependlistB, . . .)  
SORTD(listname)  
SORTD(keylistname,dependlistA,dependlistB, . . .)  
CLRLIST  
CLRLIST (clear list, STAT EDIT, item 4) clears (deletes) the  
elements of one or more lists.  
CLRLIST listnameA,listnameB, . . .  
Statistics 9-13  
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Statistical Analysis  
Pressing A 9 accesses the STAT CALC menu, where you select and perform  
statistical calculations. The TI-80 can analyze one-variable or two-variable  
statistics. Both can have associated frequency lists.  
STAT CALC  
Menu  
EDIT CALC  
1:1-VAR STATS Calculates 1-variable statistics.  
2:2-VAR STATS Calculates 2-variable statistics.  
3:LINREG(aX+b) Fits data to linear model.  
4:QUADREG  
Fits data to quadratic model.  
5:LINREG(a+bX) Fits data to linear model.  
6:LNREG  
7:EXPREG  
8:PWRREG  
Fits data to logarithmic model.  
Fits data to exponential model.  
Fits data to power model.  
Selecting and  
Performing a  
Statistical  
To select and perform statistical calculations:  
1. Select a calculation type by pressing its corresponding  
number on the STAT CALC menu. The name of the  
calculation is copied to the Home screen.  
Calculation  
2. Enter the name(s) of the list(s) to be used in the  
calculation. If you enter more than one list name, separate  
them by commas.  
3. Press ¸ to perform the calculation and display the  
results.  
Frequency of  
Occurrence for  
Data Points  
For all of the calculation types, you can include a list of data  
occurrences, or frequencies. These indicate how many times  
the corresponding data points or data pairs occur in the data  
set you are analyzing.  
For example, if L1={15.5,12.1,9.8,14.7,15} and L2={1,4,1,3,3},  
then the instruction 1-VAR STATS L1,L2 would assume that  
15.5 occurred one time, 12.1 occurred four times, 9.8 occurred  
one time, and so on.  
Frequencies must be greater than or equal to zero. At least  
one frequency in the list must be greater than zero.  
Noninteger frequencies are valid. This is useful in entering  
frequencies expressed as percentages or parts that add up to  
1. Noninteger frequencies, however, may prevent the  
calculation of certain variables.  
9-14 Statistics  
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Types of Statistical Analysis  
These calculations return statistical results based on the list(s) you reference. If  
you reference a third list name as an argument for 2-VAR STATS or any of the  
regression models, the list is interpreted as the frequencies of occurrence for  
the data pairs in the first two lists.  
1-VAR STATS  
1-VAR STATS (one-variable statistics, STAT CALC, item 1)  
analyzes data with one measured variable and calculates  
statistical results as indicated on page 9-17.  
If you reference two list names, the second list is interpreted  
as the frequency of occurrence for each data point in the first  
list.  
1-VAR STATS listname  
1-VAR STATS Xlistname,freqlistname  
2-VAR STATS (two-variable statistics, STAT CALC, item 2)  
analyzes paired data between which there is a relationship.  
This option calculates statistical results as indicated on page  
9-17.  
2-VAR STATS  
The first list you reference is the independent variable (X list).  
The second list is the dependent variable (Y list). If you  
reference a third list name, it is interpreted as the frequency of  
occurrence for each data pair in the first two lists.  
2-VAR STATS Xlistname,Ylistname  
2-VAR STATS Xlistname,Ylistname,freqlistname  
LINREG  
(aX+b)  
LINREG (aX+b) (linear regression, STAT CALC, item 3) fits  
the data to the model y=ax+b using a least-squares fit and x  
and y. It displays a (slope), b (y-intercept), and r (correlation  
coefficient).  
LINREG (aX+b) Xlistname,Ylistname  
LINREG (aX+b) Xlistname,Ylistname,freqlistname  
Statistics 9-15  
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QUADREG  
QUADREG (quadratic regression, STAT CALC, item 4) fits the  
data to the second-order polynomial y=ax2+bx+c. It displays  
a, b, and c. For three data points the equation is a polynomial  
fit; for four or more, it is a polynomial regression. At least  
three data points are required.  
QUADREG Xlistname,Ylistname  
QUADREG Xlistname,Ylistname,freqlistname  
LINREG  
(a+bX)  
LINREG (a+bX) (linear regression, STAT CALC, item 5) fits  
the data to the model equation y=a+bx using a least-squares fit  
and x and y. It displays a, b, and r (correlation coefficient).  
LINREG (a+bX) Xlistname,Ylistname  
LINREG (a+bX) Xlistname,Ylistname,freqlistname  
LNREG  
LNREG (logarithmic regression, STAT CALC, item 6) fits the  
data to the model equation y=a+b ln(x) using a least-squares  
fit and transformed values LN(x) and y. It displays a, b, and r  
(correlation coefficient).  
LNREG Xlistname,Ylistname  
LNREG Xlistname,Ylistname,freqlistname  
EXPREG  
PWRREG  
EXPREG (exponential regression, STAT CALC, item 7) fits the  
data to the model equation y=ab using a least-squares fit and  
transformed values x and LN(y). It displays a, b, and r  
(correlation coefficient).  
x
EXPREG Xlistname,Ylistname  
EXPREG Xlistname,Ylistname,freqlistname  
PWRREG (power regression, STAT CALC, item 8) fits the data  
b
to the model equation y=ax using a least-squares fit and  
transformed values LN(x) and LN(y). It displays a, b, and r  
(correlation coefficient).  
PWRREG Xlistname,Ylistname  
PWRREG Xlistname,Ylistname,freqlistname  
Note: Calculations for v, GX, GXñ, SX, sX, w, GY, GYñ, SY, sY,  
and GXY are calculated using transformed values for LNREG,  
EXPREG, and PWRREG.  
9-16 Statistics  
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Statistical Variables  
The statistical variables are calculated as indicated below. Some are displayed  
when 1-VAR STATS or 2-VAR STATS are calculated. You can access these  
variables for use in expressions through the VARS STATISTICS... menus. If you  
edit a list, all statistical variables are cleared.  
LIN, LN,  
1-VAR 2-VAR EXP, PWR  
STATS STATS REGS  
VARS  
QUADREG Menu  
Variables  
v (mean of X values)  
Ÿ
Ÿ
Ÿ
Ÿ
Ÿ
Ÿ
Ÿ
Ÿ
Ÿ
Ÿ
Ÿ
Ÿ
Ÿ
Ÿ
Ÿ
Ÿ
Ÿ
Ÿ
Ÿ
Ÿ
Ÿ
Ÿ
Ÿ
Ÿ
Ÿ
Ÿ
Ÿ
Ÿ
Ÿ
Ÿ
Ÿ
Ÿ
Ÿ
Ÿ
X/Y  
G
GX (sum of X values)  
2
2
GX (sum of X values)  
G
SX (sample standard deviation of X)  
sX (population standard deviation of X)  
n (number of data points)  
w (mean of Y values)  
X/Y  
X/Y  
X/Y  
X/Y  
G
Ÿ
GY (sum of Y values)  
2
GYñ (sum of Y values)  
G
SY (sample standard deviation of Y)  
sY (population standard deviation of Y)  
GXY (sum of X × Y)  
MINX (minimum of X values)  
MAXX (maximum of X values)  
MINY (minimum of Y values)  
MAXY (maximum of Y values)  
Q1 (1st quartile)  
X/Y  
X/Y  
G
Ÿ
Ÿ
X/Y  
X/Y  
X/Y  
X/Y  
BOX  
BOX  
BOX  
EQ  
EQ  
EQ  
EQ  
Ÿ
Ÿ
Ÿ
MED (median)  
Q3 (3rd quartile)  
a, b (regression/fit coefficients)  
a, b, c (quadratic coefficients)  
r (correlation coefficient)  
REGEQ (regression equation)  
Ÿ
Ÿ
Ÿ
Ÿ
Ÿ
Ÿ
Q1 and Q3  
The quartile Q1 is the median of the ordinals to the left of  
MED (median). The quartile Q3 is the median of the ordinals  
to the right of MED.  
Noninteger  
Frequencies  
If a frequency list contains noninteger values, SX and SY are  
undefined. No values are displayed for them in the statistical  
results. Q1, MED, and Q3 are also undefined if the frequency  
list contains noninteger values.  
Large  
If a frequency list contains a value larger than 99, Q1, MED,  
Frequencies  
and Q3 will not be calculated.  
Zero  
Frequencies  
If the frequency for an element or data pair is zero, the  
element or data pair is ignored in the calculation.  
Statistics 9-17  
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Statistical Plotting  
You can plot statistical data that you have entered in lists. The types of plots  
available include scatter plots, x-y lines, box and whisker plots, and histograms.  
You can define up to three plots at a time.  
Steps  
To plot statistical data:  
1. Enter the statistical data as lists (page 9-9 and Chapter 8).  
2. Select the statistical calculations (pages 9-14 through 9-16  
), and calculate the statistical variables (page 9-17) or fit  
the data to a model, if desired.  
3. Select or deselect Y= equations, as appropriate  
(Chapter 4).  
4. Define the statistical plot (page 9-20).  
5. Turn the plot(s) on, if necessary (page 9-21).  
6. Define the viewing window (page 9-21 and Chapter 4).  
7. Display and explore the graph by pressing ,, *,  
or +.  
Scatter Plot  
¼
¼ (scatter plot) plots the data points from XL (X list) and YL  
(Y list) as coordinate pairs, showing each point as a box (Â),  
cross (+), or dot (¦). XL and YL must be the same length. They  
can be the same list.  
XYLine  
½
½ (XYLine) is a scatter plot in which the data points are  
plotted and connected in the order in which they appear in XL  
and YL. You may want to sort the lists with SORTA( or  
SORTD( before plotting.  
9-18 Statistics  
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Box Plot  
¾
¾ (box plot) plots one-variable data. The whiskers on the plot  
extend from the minimum data point in the set (MINX) to the  
first quartile (Q1) and from the third quartile (Q3) to the  
maximum point (MAXX). The box is defined by Q1, the  
median (MED), and Q3 (page 9-17).  
Box plots are plotted with respect to XMIN and XMAX, but  
ignore YMIN and YMAX. When two box plots are plotted, the  
first plots at the top of the screen and the second plots in the  
middle. When three are plotted, the first plots at the top, the  
second in the middle, and the third at the bottom.  
Histogram  
¿
¿ (histogram) plots one-variable data. XSCL determines the  
width of each bar, beginning at XMIN. (XMAX – XMIN)àXSCL  
must be  31. A value occurring on the edge of a bar is  
counted in the bar to the right.  
Frequencies in  
Stat Plots  
The frequency list specified for a statistical plot works just  
like the frequency lists specified for other statistical  
calculations (pages 9-14 through 9-16).  
If you want to exclude an outlying data point from a plot,  
enter a zero for that value in the frequency list to prevent  
having to change the data lists.  
Statistics 9-19  
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Defining the  
Plots  
To define plots:  
1. Press 2 ". The STAT PLOTS screen shows the  
current plot definitions.  
2. Select the plot to define (PLOT1, PLOT2, or PLOT3).  
3. If you wish to plot the statistical data immediately, select  
ON. You can define a plot at any time and leave it OFF.  
The definition will be available in the future.  
4. Select the type of plot. The options change appropriately.  
¦
¦
¦
¦
¼ (scatter plot):  
½ (XYLine):  
¾ (box plot):  
¿ (histogram):  
XL  
XL  
XL  
XL  
YL  
YL  
MARK  
MARK  
F
F
Where:  
¦
¦
¦
¦
XL is the list of independent data.  
YL is the list of dependent data.  
F is the frequency (1 is used if no list is specified).  
MARK is , +, or ¦.  
9-20 Statistics  
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Turning Plots Off PLOTSOFF and PLOTSON allow you to turn statistical plots  
or On  
off or on from the Home screen or a program. Used without  
plot#, they turn all plots off or all plots on. Used with plot#,  
they turn specific plots off or on.  
PLOTSOFF or PLOTSON  
PLOTSOFF plot#,plot#, . . .  
PLOTSON plot#,plot#, . . .  
For example, PLOTSOFF followed by PLOTSON 3 turns all  
plots off and then turns PLOT3 on.  
Defining the  
Statistical plots are displayed on the current graph. You may  
Viewing Window define the viewing window by pressing ) and then  
entering values for the Window variables.  
Tracing a Stat  
Plot  
When you trace a scatter plot or XYLine, tracing begins at the  
first element in the lists.  
When you trace a box plot, tracing begins at MED (the  
median). Press 6 to trace to Q1 and MINX. Press 9 to trace  
to Q3 and MAXX.  
When you trace a histogram, the cursor moves to the top  
center of each column, starting at the first column.  
When you press 7 or 8 to move to another plot or Y=  
function, tracing moves to the current or beginning point on  
that plot.  
Statistics 9-21  
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Statistical Analysis in a Program  
You can enter statistical data, calculate statistical results, and fit data to models  
from a program.  
Entering Stat  
Data  
Enter the statistical data directly into lists (Chapter 8) in the  
program.  
Statistical  
Calculations  
To calculate statistical results or fit data to a model from a  
program:  
1. On a blank line in the program editor, select the type of  
calculation from the STAT CALC menu.  
2. Enter the names of the lists, separated by commas, to use  
in the calculation.  
Note: To display a regression equation and coefficients from  
a program, the regression function must be the last statement  
in the program. If it is not the last statement, the regression  
equation will be evaluated and stored, but the results will not  
be displayed.  
9-22 Statistics  
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Statistical Plotting in a Program  
To display a statistical plot, you may define the plot(s), then turn the plot(s) on,  
and then display the graph. If you do not define the plot, the current definitions  
are used.  
Defining a Stat  
Plot in a  
Program  
To define a statistical plot in a program:  
1. Enter the data into list(s). On a blank line in the program  
editor, press 2 " to display the PLOTS menu.  
2. Select the plot to define. PLOT1(, PLOT2(, or PLOT3( is  
copied to the cursor location.  
3. Press 2 " 9 to display the TYPE menu. Select  
the type of plot. ¼ (scatter), ½ (XYLine), ¾ (box), or ¿  
(histogram) is copied to the cursor location.  
4. Press b. Enter the list names, separated by commas.  
5. (This step is for ¼ and ½ only.) Press b. Press 2  
" 9 9 to display the MARK menu. Select the  
+
mark. , , or  
. is copied to the cursor location.  
6. Press d and ¸ to complete the command line.  
7. Press 2 " 5 to copy PLOTSON to the command  
line and the number of the plot (1, 2, or 3) to turn on. Press  
¸ to complete the command line.  
Note that PLOTSOFF in the  
example program ensures that all  
other plots are turned off.  
Statistics 9-23  
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Displaying a Stat To display a plot, use any of the Zoom instructions (Chapter  
Plot from a  
4), or use the DISPGRAPH instruction (Chapter 10).  
Program  
9-24 Statistics  
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Chapter 10: Programming  
This chapter describes specific programming instructions and explains how to  
enter and execute programs on the TI.80.  
Chapter  
Contents  
Getting Started: Rolling a Die ....................... 10-2  
About TI-80 Programs ............................. 10-4  
Creating and Executing Programs .................. 10-5  
Editing Programs ................................. 10-6  
PRGM CTL (Control) Instructions .................. 10-7  
PRGM I/O (Input/Output) Instructions ............... 10-11  
Calling Other Programs ........................... 10-14  
Programming 10-1  
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Getting Started: Rolling a Die  
Getting Started is a fast-paced introduction. Read the chapter for details.  
A program is a set of commands that can be executed sequentially, as if they  
had been entered from the keyboard. Write a simple program to simulate the  
rolling of a single die. It should prompt for the number of rolls and then store the  
results of the rolls in a list.  
1. Press K 9 9 to display the PRGM NEW menu.  
2. Press ¸ to select CREATE NEW. (The keyboard  
is now in ALPHA-LOCK.) Type R O L L as the name  
of the program, and press ¸. You are now in the  
program editor. The : (colon) in the first column of  
the second line indicates that this is the beginning of  
a command line.  
3. Press K 9 to access the PRGM I/O menu. Press  
4. CLRHOME is copied to cursor location. Press  
¸ to complete the instruction and move to the  
next line.  
4. Press 0 § 2 = 3 2 ¢. This sets the  
dimension of Lã (the list where the results of the rolls  
will be stored) to 0. Press ¸ to complete the  
instruction and move to the next line.  
5. Press K 9 1 to copy INPUT to the cursor  
location. Press 2 < ã"ä ROLLS 2 D 1  
? ã"ä b ? R to prompt the user to input the  
number of rolls. Press ¸ to complete the  
instruction.  
6. Press K 4 to copy FOR( to the cursor location.  
Press ? I b 1 b ? R b 1 d. Press ¸  
to complete the instruction.  
10-2 Programming  
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7. Press I 6 to access the MATH PRB menu. Press  
5 (to copy RANDINT( to the cursor location) 1 b 6 d  
§ 2 ¢ c ? I d to generate random  
integers from 1 to 6 and store them into element I of  
L1. Press ¸ to complete the instruction.  
8. Press K 9 2 to select DISP (display), which is  
copied to the cursor location. Press 2 ¢ c ?  
I d. This instruction displays the value of element I  
(the result of the last roll) in L1. Press ¸ to  
complete the instruction.  
9. Press K 6 to select PAUSE, which is copied to the  
cursor location. This pauses the program after  
displaying the result of the last roll. Press ¸ to  
complete the instruction.  
10. Press K 5 to select END, which is copied to the  
cursor location. END identifies the end of the group  
of commands in the FOR( loop. Press ¸ to  
complete the instruction.  
11. Press K 9 2 2 ¢ to display the list of all the  
roll results. Press ¸ to complete the instruction.  
12. Press 2 . M K. Move the cursor to the  
program name ROLL. Press ¸. Press ¸ again  
from the Home screen to execute PRGM_ROLL.  
Programming 10-3  
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About TI-80 Programs  
Most features of the TI.80 are accessible from programs. Programs can access  
all variables and named items. The number of programs that the TI.80 can store  
is limited only by available memory.  
Notes about  
Programs  
Programs are identified by names of up to seven characters,  
beginning with a letter.  
A program consists of a series of program commands, which  
begin with a : (colon). A program command can be an  
expression (a command, usually a combination of variables,  
functions, and numeric values, that returns a value to ANS) or  
an instruction (a command, such as GRIDON or PT-ON(, that  
does not return a value to ANS).  
The TI-80 checks for errors when you execute the program,  
not as you enter or edit the program.  
Variables and lists saved in memory are global; that is, they  
can be accessed from all programs. Storing a new value to a  
variable or list in a program changes the value in memory  
during program execution.  
As calculations are made in programs, the TI-80 updates ANS,  
just as it would if the calculations were done on the Home  
screen. Programs do not update Last Entry as each command  
is executed.  
"Breaking" a  
Program  
Pressing ´ stops program execution. When you press ´  
during program execution, the ERR: BREAK menu is  
displayed.  
¦
¦
To go to where the interruption occurred, select GOTO.  
To return to the Home screen, select QUIT.  
Memory  
The size of programs you can store is limited only by available  
Management and memory. To access the MEMORY menu, press 2 ¯ from  
Erasing  
Programs  
the Home screen. Memory status is displayed on the MEMORY  
CHECK RAM... screen. To increase available memory, you can  
delete items, including other programs, from the  
MEMORY DELETE... screen (Chapter 12).  
Note: Each token in a program takes 1 byte. For example,  
SIN 1.23 takes 5 bytes.  
10-4 Programming  
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Creating and Executing Programs  
Access the program editor by pressing K. Then either choose to create a  
new program or edit an existing program. In general, anything that can be  
executed from the Home screen can be included in a program. A program  
command always begins with a colon (:).  
Creating a New  
Program  
To create a new program:  
1. Press K 9 9 to display the PRGM NEW menu. Press  
¸ to select CREATE NEW.  
2. The keyboard is in ALPHA-LOCK. Enter the name you  
want for the program, followed by ¸. The name may  
have one to seven characters (AZ, q, 09) and must begin  
with a letter.  
3. Enter the program commands.  
Entering  
Program  
Commands  
A colon (:) indicates the beginning of each program command.  
To enter more than one command on a line, separate them  
with a colon, just as you would on the Home screen. Press  
¸ to indicate the end of a command line.  
When a command is longer than one line on the screen, it  
wraps to the next line. 2 6 and 2 9 move the cursor to  
the beginning and end of a command line.  
In the program editor, if you press a key that accesses a menu,  
the menu screen temporarily replaces the program edit  
screen. When you make a selection or press M, you are  
returned to the program editor.  
Leaving the  
Program Editor  
When you finish entering or editing a program, press 2 .  
to return to the Home screen. You must be on the Home  
screen to execute a program.  
Executing a  
Program  
To execute a program:  
1. From a blank line on the Home screen, press K to  
display the PRGM EXEC menu. The names of all existing  
programs are listed in alphabetical order.  
2. Select the program. PRGM_ and the program name are  
copied to the Home screen; for example, PRGM_ROLL.  
3. Press ¸ to begin program execution. While the  
program is executing, the busy indicator is displayed.  
Programming 10-5  
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Editing Programs  
The program editor also lets you edit an existing program. As you edit, you can  
enter commands just as you did when you created the program.  
Editing a  
Program  
To edit a program:  
1. Press K 9 to display the PRGM EDIT menu.  
2. Select the name of an existing program. The program  
editor and the commands in that program are displayed.  
3. Edit the program by changing, inserting, or deleting  
commands, as needed.  
Changing  
Move the cursor to the command you want to change.  
Instructions  
¦
Position the cursor, and then make the changes by typing  
over the command or using 4 or 2 /.  
¦
Press M to clear (blank) all program commands on  
the command line (The leading colon is not deleted.), and  
then enter a new program command.  
Inserting a New  
Command Line  
To insert a new command line, position the cursor where you  
want to insert the new line, press 2 / to put the TI-80 in  
insert mode, and then press ¸.  
Deleting a  
To delete a command line, press M to clear the line, and  
Command Line  
then press 4 to delete the colon.  
Note: All programs end with a blank command line; the colon  
on this line cannot be deleted.  
10-6 Programming  
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PRGM CTL (Control) Instructions  
PRGM CTL (program control) instructions are accessed only from within the  
program editor. They direct the flow within an executing program, making it easy  
to repeat or skip commands during program execution. While the program editor  
is displayed, press K. The selected menu item is copied to the cursor  
location.  
PRGM CTL  
Menu  
CTL I/O EXEC  
1:IF  
Creates a conditional test.  
Used with IF.  
Used with IF-THEN.  
Creates incrementing loop.  
Signifies end of loop, IF-THEN, or ELSE.  
Pauses program execution.  
Defines a label.  
2:THEN  
3:ELSE  
4:FOR(  
5:END  
6:PAUSE  
7:LBL  
8:GOTO  
9:PRGM_  
0:RETURN  
A:STOP  
Goes to a label.  
Executes a program as a subroutine.  
Returns from a subroutine.  
Stops program execution.  
Controlling  
Program Flow  
Program control instructions tell the TI-80 which command to  
execute next in a program. IF checks a condition that you  
define to determine what command to execute next. The  
condition frequently uses relational tests (Chapter 2), such as  
IF A<7:A+1!A.  
IF  
IF (PRGM CTL, item 1) is used for testing and branching. If the  
condition is false (zero), the command immediately following  
IF is skipped. If the condition is true (nonzero), that command  
is executed. IF instructions can be nested.  
:IF condition  
:command if true  
:command  
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IF-THEN  
END  
THEN (PRGM CTL, item 2) following an IF executes a group of  
commands if the condition is true (nonzero).  
END (PRGM CTL, item 5) identifies the end of the group.  
:IF condition  
:THEN  
:command if true  
:...  
:END  
:command  
IF-THEN-ELSE  
END  
ELSE (PRGM CTL, item 3) following IF-THEN executes a  
group of commands if the condition is false (zero).  
END (PRGM CTL, item 5) identifies the end of the group.  
:IF condition  
:THEN  
:command if true  
:...  
:ELSE  
:command if false  
:...  
:END  
:command  
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FOR(  
END  
FOR( (PRGM CTL, item 4) is used for looping and  
incrementing. It increments the variable from the beginning  
value to the ending value, by the specified increment. The  
ending value is a maximum or minimum value that is not to be  
exceeded. The increment is optional (if not specified, 1 is  
used) and can be negative (ending value < beginning value).  
END identifies the end of the loop. FOR( loops can be nested.  
:FOR(variable,begin,end,increment)  
:command while end not exceeded  
:...  
:END  
:command  
END (PRGM CTL, item 5) identifies the end of a group of  
commands. Each FOR( and each IF-THEN or IF-THEN-ELSE  
group must have an END at the “bottom.”  
END  
PAUSE  
PAUSE (PRGM CTL, item 6) suspends execution of the  
program so that you can see answers or graphs. During the  
pause, the dotted pause indicator is displayed. When DISP or  
DISPGRAPH is executed, the appropriate screen is displayed.  
Press ¸ to resume program execution.  
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LBL  
LBL (label) and GOTO (go to) are used together for branching.  
GOTO  
LBL (PRGM CTL, item 7) gives a label to a command line in a  
program. The label is one character (A–Z, 0–9, or q).  
LBL label  
GOTO (PRGM CTL, item 8) causes the program to branch to  
the command line with the same label.  
GOTO label  
PRGM_  
PRGM_ (PRGM CTL, item 9) calls (executes) other programs  
as subroutines (pages 10-14). When you select PRGM_, it is  
copied to the cursor location. You may type the letters of an  
existing program name. You may also enter the name of a  
program you have not yet created.  
When encountered, the command executes the specified  
program and then returns to the calling program. Execution  
continues with the command following PRGM_programname.  
PRGM_programname  
RETURN  
RETURN (PRGM CTL, item 0) quits the subroutine and returns  
to the calling program (pages 10-14), even if it is encountered  
within nested loops. (Any loops are ended.) There is an  
implied RETURN at the end of any program called as a  
subroutine. Within the main program, RETURN stops program  
execution and returns to the Home screen.  
STOP  
STOP (PRGM CTL, item A) stops execution of a program and  
returns you to the Home screen. STOP is optional at the end  
of a program. There is an implied stop at the end of the main  
program that is being executed.  
10-10 Programming  
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PRGM I/O (Input/Output) Instructions  
The PRGM I/O (program input/output) instructions are accessed only from the  
program editor. They control input to and output from a program, allowing you  
to enter values and display answers during program execution. While the  
program editor is displayed, press K. The selected menu item is copied to  
the cursor location.  
PRGM I/O  
Menu  
CTL I/O EXEC  
1:INPUT  
2:DISP  
Enters a value or displays the current graph.  
Displays text, value, or the Home screen.  
3:DISPGRAPH Displays the current graph.  
4:CLRHOME Clears the Home screen.  
Displaying a  
Graph with  
INPUT  
INPUT without a variable displays the current graph. You can  
move the free-moving cursor, which updates X and Y. The  
dotted pause indicator is displayed. Press ¸ to resume  
program execution.  
For example, INPUT during program execution displays:  
Programming 10-11  
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Storing a  
Variable Value  
with INPUT  
INPUT with a variable displays a ? prompt during program  
execution. The value for the variable may be a real number, a  
list, or Y= function. During program execution, enter a value  
(a real number, an expression, or a list), and press ¸. The  
value is evaluated and stored to the variable, listname, or Y=  
function, and the program resumes execution.  
INPUT variable  
INPUT listname  
INPUT Yname  
You can enter a string of up to 16 characters to prompt for the  
value to be entered. During program execution, enter a value,  
and press ¸ after the prompt. The value is stored to the  
variable, listname, or Y= function, and the program resumes  
execution.  
INPUT "text",variable  
INPUT "text",listname  
INPUT "text",Yname  
Note: When you input lists and expressions during program  
execution, you must include the braces ({ }) around the list  
elements and quotation marks (") around expressions.  
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Displaying the  
Home Screen  
DISP (display, PRGM I/O, item 2) with no value displays the  
Home screen. To view the Home screen during program  
execution, follow the DISP instruction with a PAUSE.  
Displaying  
Values and  
Messages  
DISP (display, PRGM I/O, item 2) with one or more values  
displays the value of each.  
DISP value  
DISP valueA,valueB...  
¦
¦
If value is a variable, the current value is displayed.  
If value is an expression, it is evaluated and then  
displayed, according to the current mode settings, on the  
right of the following line.  
¦
If value is text within " marks, it displays on the left of the  
current display line.  
For example, DISP "ANSWER IS",2 displays:  
If PAUSE is encountered after DISP, the program halts  
temporarily so that you can examine the screen. Press ¸  
to resume program execution.  
Note: A statement that results in a value will display without  
using DISP, if it is the last statement (other than STOP, END,  
and PAUSE) in the program.  
DISPGRAPH  
CLRHOME  
DISPGRAPH (display graph, PRGM I/O, item 3) displays the  
current graph. If PAUSE is encountered after DISPGRAPH,  
the program halts temporarily so you can examine the screen.  
Press ¸ to resume execution.  
CLRHOME (clear Home screen, PRGM I/O, item 4) clears the  
Home screen during execution and places the cursor in the  
upper left corner; however, program execution does not pause  
unless PAUSE is encountered.  
Programming 10-13  
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Calling Other Programs  
On the TI.80, any program can be called from another program as a subroutine.  
Enter the name of the program to use as a subroutine on a line by itself.  
Calling a  
Program from  
Another  
To call one program from another, begin on a blank line in the  
program editor and do one of the following.  
¦
Press K 6 to display the PRGM EXEC menu, and  
select the name of the program. PRGM_ and the name are  
copied to the cursor location.  
Program  
¦
Select PRGM_ from the PRGM CTL menu and then type  
the letters of the programname.  
PRGM_programname  
When this instruction is encountered during program  
execution, the next command that the program executes is the  
first command in the second program. Execution continues  
with the subsequent command in the first program when it  
encounters either a RETURN instruction or when the implied  
RETURN at the end of the called program is encountered.  
Notes about  
Calling  
Variables are global.  
A label used with GOTO and LBL is local to the program in  
which it is located. A label in one program is not “known” by  
another program. You cannot use GOTO to branch to a label  
in another program.  
Programs  
RETURN exits a subroutine and returns to the calling  
program, even if encountered within nested loops.  
10-14 Programming  
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Chapter 11: Applications  
This chapter contains application examples that incorporate the TI.80 features  
described in the preceding chapters. Several of the examples use programs.  
Chapter  
Contents  
Probability Experiments: Coins, Dice, and Spinners ... 11-2  
The Unit Circle and Trigonometric Curves............ 11-3  
Program: Newton’s Numerical Solve Routine ......... 11-4  
Program: Numerical Integration..................... 11-6  
Program: Window Variables Store and Recall ......... 11-8  
Graphing the Inverse of a Function .................. 11-10  
Graphing a Piecewise Function ..................... 11-12  
Graphing Inequalities .............................. 11-14  
Graphing a Polar Equation ......................... 11-15  
Program: Guess the Coefficients .................... 11-16  
Applications 11-1  
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Probability Experiments: Coins, Dice, and Spinners  
The RANDINT( (random integer) function can be used for probability  
experiments. RANDINT( takes two arguments that define a set of integers from  
which to draw for the probability experiments below.  
Problem  
Using RANDINT( from the MATH PRB menu, devise  
probability experiments that employ the toss of a coin, the roll  
of two dice, and the spin of a wheel.  
Procedure  
For the coin tossing experiment, enter RANDINT(0,1) from the  
Home screen. 0 = tails and 1 = heads. Press ¸ repeatedly  
to generate the coin tosses.  
You can also write a simple program to display “heads” or  
“tails” for each coin toss.  
You can simulate the rolling of two dice by adding together  
the result from each die after a roll. On the Home screen,  
enter RANDINT(1,6)+RANDINT(1,6) and press ¸  
repeatedly.  
You can simulate spinning a wheel with the numbers 1 to 100  
using the RANDINT( function. Enter RANDINT(1,100) on the  
Home screen and press ¸ repeatedly.  
11-2 Applications  
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The Unit Circle and Trigonometric Curves  
You can use the parametric graphing feature of the TI.80 to show the  
relationship between the unit circle and any trigonometric curve.  
Problem  
Graph the unit circle and the sine curve to demonstrate  
graphically the relationship between them.  
Any function that can be plotted in function graphing can be  
plotted in parametric graphing by defining the X component  
as T and the Y component as F(T).  
Procedure  
Following this procedure to solve the problem.  
1. Press 3 and select RADIAN, PARAM, and SIMUL.  
2. Press ) and set the Window variables.  
TMIN = 0  
TMAX = 2p  
TSTEP = .1  
XMIN = .2  
XMAX = 2p  
XSCL = 2  
YMIN = .3  
YMAX = 3  
YSCL = 1  
3. Press ( and enter the expressions to define the unit  
circle centered at (L1,0).  
X1îT=COS Tì1  
Enter the expressions to define the sine curve.  
X2î=T Y2î=SIN T  
Y1î=SIN T  
Turn off all other functions.  
4. Press , to see the SIN function “unwrap” from the  
unit circle.  
Note: The “unwrapping” can be generalized. Replace SIN T in  
Y2î with any other trig function to “unwrap” that function.  
Applications 11-3  
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Program: Newton’s Numerical Solve Routine  
This program uses the Newton-Raphson method to find the roots (zeros) of a  
function numerically.  
x
Problem  
Program  
Find the roots of e ì3X.  
This program uses the Newton-Raphson method to find a root  
of Y1 based on an initial guess. The program prompts for the  
initial guess. One way to make this initial guess is to graph  
and trace the function, and then enter X as the guess.  
PROGRAM:NEWTON  
:INPUT "INITIAL X=",X  
:LBL N  
Input initial guess.  
Begin loop.  
:XìY1/NDERIV(Y1,X,X)R  
:DISP R  
Calculate new root.  
:PAUSE  
:IF ABS (XìR)ABS (X/1í10)  
:STOP  
Test for convergence.  
:RX  
:GOTO N  
Estimate with new root.  
Procedure  
Follow this procedure to solve the problem.  
1. Press 3 and select FUNC.  
2. Enter the program.  
3. Press (. Enter the expression eõì3X to define Y1.  
4. Graph the function using ZDECIMAL from the ZOOM  
menu.  
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5. Press + and move the cursor close to the left root.  
The variables X and Y are updated as you move the cursor.  
6. From a blank line on the Home screen, execute the  
program NEWTON.  
7. Enter X as the initial guess, and press ¸ repeatedly.  
The program stops when the relative difference between  
the new root estimate and the previous root estimate is  
less than XíL10.  
8. When program execution is complete, evaluate the  
function at the estimated root.  
Repeat the steps in this procedure to find the other root.  
Applications 11-5  
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Program: Numerical Integration  
This program uses Simpson’s method to estimate the definite integral of a  
function.  
Problem  
Program  
Estimate the definite integral of  
1.5  
5
0
(6ì6x )dx  
and graph the area of the integral.  
The program estimates the definite integral for Y1 using  
Simpson’s method. It prompts for the lower and upper limits  
of integration and the number of divisions.  
PROGRAM:SIMPSON  
:INPUT "LOWER LIMIT=",A  
:INPUT "UPPER LIMIT=",B  
:INPUT "N DIVISIONS=",D  
:0S  
Input lower limit.  
Input upper limit.  
Input # of divisions.  
Initialize sum variable.  
Calculate division width.  
Begin calculation loop.  
Calculate left point.  
Calculate right point.  
Calculate midpoint.  
Calculate division sum and  
add to total.  
:(BìA)/(2×D)W  
:FOR(J,1,D,1)  
:A+2(Jì1)WL  
:A+2JWR  
:(L+R)/2M  
:W(Y1(L)+4Y1(M)+Y1(R))  
/3+SS  
:END  
:DISP "AREA="  
:DISP S  
Display results.  
Procedure  
Follow this procedure to solve the problem.  
1. Enter the program.  
2. Press ( and enter the function in Y1. Turn any other  
functions off.  
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3. Set the Window variables.  
4. Execute the program SIMPSON from a clear Home screen,  
entering the limits and divisions as you are prompted.  
5. You can display the calculated area graphically, using  
SHADE( from a clear Home screen.  
Applications 11-7  
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Program: Window Variables Store and Recall  
The program below lets you store the values for the current Window variables,  
and it lets you display a graph using previously stored values. It also  
demonstrates a method for including menus in a program.  
Program  
PROGRAM:WINMEM  
:CLRHOME  
:DISP "WINDOW MEMORY"  
:DISP "1:STORE WINDOW"  
:DISP "2:RECALL WINDOW"  
:DISP "3:QUIT"  
:DISP " "  
Present menu of  
choices.  
:DISP "ENTER 1,2, OR 3"  
:INPUT M  
:IF M=1  
:GOTO S  
:IF M=2  
:GOTO R  
Evaluate menu  
selection.  
:GOTO Q  
:LBL S  
:XMINA  
:XMAXB  
:XSCLC  
Store current graph  
Window variable values.  
:YMIND  
:YMAXE  
:YSCLF  
:DISP "WINDOW STORED"  
:GOTO Q  
:LBL R  
:AXMIN  
:BXMAX  
:CXSCL  
:DYMIN  
:EYMAX  
:FYSCL  
:DISPGRAPH  
:GOTO Q  
:LBL Q  
Display graph with  
previously stored  
variable values.  
Quit program.  
:STOP  
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Procedure  
Follow this procedure to see how the program works.  
1. Execute the program WINMEM from a blank Home screen.  
The program prompts with three options.  
¦ Store the Window variables you are currently using.  
¦ View a graph using a previously stored set of Window  
variables.  
¦ Quit the program.  
2. Press 1, 2, or 3 and then ¸ to respond to the prompts.  
The Window values are stored in variables A, B, C, D, E,  
and F.  
Applications 11-9  
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Graphing the Inverse of a Function  
You can use the parametric graphing feature of the TI.80 to graph the inverse  
relation of any function by defining the function in XãT and YãT and its inverse in  
XäT and YäT.  
Problem  
The function Y=.2X3ì2X+6 can be expressed in parametric  
form as XT=T and YT=.2T3ì2T+6.  
The inverse relation of the function can be expressed in  
parametric form as XT=F(T) and YT=T. For example,  
Y=.2X3ì2X+6 would be expressed as XT=.2T3ì2T+6 and  
YT=T.  
Graph the function Y=.2X3ì2X+6 and its inverse.  
Follow this procedure to solve the problem.  
1. Select Param, CONNECTED, and Simul modes.  
2. Change the Window variable values.  
Procedure  
Tmin=L10  
Tmax=10  
Tstep=.4  
Xmin=L15  
Xmax=15  
Xscl=1  
Ymin=L9  
Ymax=9  
Yscl=5  
3. Enter the expressions to define the function in parametric  
form.  
X1î=T  
Y1î=.2Tò–2T+6  
4. Enter the expressions to define the inverse in parametric  
form.  
X2î=.2Tò–2T+6  
Y2î=T  
11-10 Applications  
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5. Enter the expressions to define the line Y=X, about which  
the graph of the function and the graph of its inverse are  
symmetric. That is, the reflection of the graph of the  
function through the line Y=X produces the graph of its  
inverse.  
X3î=T  
Y3î=T  
6. Press , to plot the graph. Press +, and then  
press 9 several times (until the cursor appears). Next,  
press 8 and 7 several times to move the cursor from a  
point on the relation to the reflected point and back again.  
Note: The expressions to define the inverse can be  
generalized.  
X1î=Y2î  
Y1î=X2î  
Applications 11-11  
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Graphing a Piecewise Function  
The test functions of the TI.80 can be used to build piecewise defined functions.  
Problem  
Define and graph this piecewise defined function.  
xñ, for x3  
f(x)=  
1.5x+1, for 3<x<5  
6ìx, for x5  
The TEST functions, which return 1 if true and 0 if false, can  
be used to build piecewise defined functions. For example,  
when x is 4 (x3) is false and will return 0.  
Procedure  
Follow this procedure to solve the problem.  
1. Press 3 and select FUNC.  
2. Enter the first piece of the function in the Y= editor. This  
piece is f(x)=xñ for x3. It is entered as (xñ)(x3). Yã is  
then equivalent to xñ×1 for x3 and xñ×0 for x>3.  
3. Add the second piece of the function in the Y= editor. This  
piece is f(x)=1.5x+1 for 3<x<5. It is entered as  
(1.5x+1)(3<x)(x<5).  
When x is less than 3, the test (3<x) returns 0, and the test  
(x<5) returns 1. In this case, the second piece of the  
function is equivalent to (1.5x+1)×0×1, which is 0. Only  
when both of these tests are true will the second piece of  
this function be anything but 0.  
11-12 Applications  
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4. Add the third piece of the function to Y1. This piece is  
f(x)=6ìx for x5. It is entered as (6ìx) (x5). When x is  
greater than or equal to 5, the test (x5) returns 1. The  
third piece of the function is then equivalent to (6ìx)×1.  
When X is less than 5, the test (x5) returns 0. The third  
piece of the function is then equivalent to (6ìx)×0.  
5. Enter these Window variable values.  
Xmin=ë2  
Xmax=8  
Xscl=2  
Ymin=ë2  
Ymax=10  
Yscl=1  
6. Graph the piecewise function first in CONNECTED and  
then DOT mode. Select CONNECTED on the MODE screen,  
and then press ,. Then select DOT on the MODE  
screen, and press ,.  
CONNECTED  
DOT  
Applications 11-13  
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Graphing Inequalities  
Examine the inequality .4Xòì3X+5<.2X+4 graphically. Use the TEST functions to  
explore the values of X where the inequality is true and where it is false.  
Procedure  
1. Press 3. Select DOT, SIMUL, and the default mode  
settings. Press 2 ", and turn off all stat plots.  
2. Press (, and turn off all functions. Enter the left side of  
the inequality as Y1, the right side as Y2, and the statement  
of the inequality as Y3. Y3 evaluates to 1 if true and 0 if  
false.  
3. Press ), and enter these Window variable values.  
Xmin=ë10  
Xmax=10  
Xscl=5  
Ymin=ë10  
Ymax=10  
Yscl=5  
4. Press +. Press 8 8 to move to Y3. Trace the  
inequality, observing the value of X. Y3 is 1 when Y1 < Y2,  
and Y3 is 0 when Y1 Y2.  
5. Press ( and turn off Y1 and Y2. Enter equations to graph  
only the inequality.  
6. Press +. Notice that the values of Y3 and Y4 are zero  
where the inequality is false.  
11-14 Applications  
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Graphing a Polar Equation  
The parametric graphing feature of the TI.80 can be used to graph polar  
equations. Graph the Spiral of Archimedes, the name given to the curve defined  
by the polar equation r=aq.  
Problem  
A polar equation r=f(q) can be graphed by applying the  
conversion formulas, x=f(q) cos(q) and y=f(q) sin(q). Thus,  
the Spiral of Archimedes can be expressed parametrically as:  
x = .5 q cos(q)  
y = .5 q sin(q)  
Procedure  
Follow this procedure to solve the problem.  
1. Select PARAM mode. Choose the defaults for the other  
mode settings.  
2. Enter the expressions to define the parametric equation in  
terms of T.  
3. Set the Window variables to the following values.  
Tmin=0  
Tmax=25  
Tstep=π8  
Xmin=L10  
Xmax=10  
Xscl=1  
Ymin=L10  
Ymax=10  
Yscl=1  
4. Press , to display the Spiral of Archimedes.  
Applications 11-15  
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Program: Guess the Coefficients  
This program generates a function in the form A×SIN(BX) with random integer  
coefficients between 1 and 10. Seven data points from the function are plotted.  
You are prompted to guess the coefficients, which are plotted as C×SIN(DX). The  
program continues until your guess is correct. It can be modified for other  
functions.  
PROGRAM:GUESS  
:FUNC:RADIAN  
:-31(p/12)"XMIN  
:31(p/12)"XMAX  
:p/2"XSCL  
Program  
Set viewing window.  
:-10"YMIN  
:10"YMAX  
:1"YSCL  
:"A×SIN (BX)""Y1  
:RANDINT(1,10)"A  
:RANDINT(1,10)"B  
:PLOTSOFF: FNOFF  
:DISPGRAPH  
Initialize  
coefficients.  
Display data points.  
Prompt for guesses.  
:SEQ(XMIN+I×X,I,0,62,9)"L1  
:Y1(L1)"L2  
:PLOT1(¼,L1,L2,)  
:DISPGRAPH  
:PAUSE  
:"C×SIN (DX)""Y2  
:LBL W  
:CLRHOME  
:DISP "C×SIN (DX)"  
:INPUT "C=",C  
:INPUT "D=",D  
:DISPGRAPH  
:PAUSE  
:IF C=A  
:DISP "C IS OK"  
:IF C>A  
:DISP "C IS TOO HIGH"  
:IF C<A  
:DISP "C IS TOO LOW"  
:IF D=B  
Display  
results.  
:DISP "D IS OK"  
:IF D>B  
:DISP "D IS TOO HIGH"  
:IF D<B  
:DISP "D IS TOO LOW"  
:PAUSE  
:IF((C=A)×(D=B))=1  
Quit if guesses are  
correct.  
:STOP  
:GOTO W  
11-16 Applications  
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Chapter 12: Memory Management  
This chapter describes how to manage memory on the TI.80. To increase the  
amount of memory available for use, occasionally you may want to delete stored  
items that you are no longer using. You can also reset the calculator, erasing all  
data and programs.  
Chapter  
Contents  
Checking Available Memory ........................ 12-2  
Deleting Items from Memory ....................... 12-3  
Resetting the TI-80 ................................ 12-4  
Memory Management 12-1  
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Checking Available Memory  
The MEMORY CHECK RAM screen displays the total amount of available  
memory and the amount of memory used by each variable type. This allows you  
to determine the amount of memory available for new items such as programs  
and the amount used by old items that you no longer need.  
Displaying the  
MEM FREE  
Screen  
To check the amounts of available and used memory:  
1. Press 2 ¯ to display the MEMORY menu.  
2. Press 1 or ¸ to select CHECK RAM....  
The amount of available memory and the number of bytes  
used by each variable type are shown on the right.  
3. To leave the CHECK RAM display:  
¦
¦
Press 2 . to go to the Home screen.  
Press 2 ¯ to return to the MEMORY menu.  
12-2 Memory Management  
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Deleting Items from Memory  
You can delete the contents of any variable (real number, list, or Y= function) or  
program from memory to increase available memory.  
Deleting an Item  
To delete an item:  
1. Press 2 ¯ to display the MEMORY menu.  
2. Press 2 to select DELETE... A screen showing all variables  
currently in use and the amount of memory used by each  
is displayed.  
The file names are listed in the following order:  
¦
¦
¦
¦
Program names  
List names  
Y= equation names  
Numeric variable names  
3. Use 7 and 8 to position the cursor, which is indicated by  
ú in the left column, next to the item you want to delete;  
and press ¸. The item is deleted immediately.  
You can continue to delete individual items from this screen.  
To leave the DELETE display:  
¦
¦
Press 2 . to go to the Home screen.  
Press 2 ¯ to return to the MEMORY menu.  
Note: Some system variables ANS and statistical variables  
such as REGEQ, for example cannot be deleted. These system  
variables are not shown on the DELETE display.  
Memory Management 12-3  
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Resetting the TI-80  
Resetting the TI.80 restores memory to the factory settings, including deleting  
the contents of all variables and programs and resetting all system variables to  
the original settings. Because you can increase available memory by deleting  
individual items, you should rarely need to reset the TI.80.  
Resetting  
To reset the TI-80:  
1. Press 2 ¯ to display the MEMORY menu.  
2. Press 3 to select RESET....  
3. Make the appropriate menu selection:  
¦
To go to the Home screen without resetting memory,  
select NO.  
¦
To reset memory, select RESET. The Home screen is  
displayed with the message MEM CLEARED.  
Note: If the screen is blank after RESET, adjust the display  
contrast. Press 2 and then press and hold 7 (to make the  
display darker) or 2 8 (to make the display lighter). You  
can press M to clear the message on the display.  
12-4 Memory Management  
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Appendix A: Tables and Reference Information  
This appendix provides a list of all TI-80 functions that you can use in  
expressions and instructions that you can use on the Home screen and in  
programs. It also includes other reference information that can help you.  
Appendix  
Contents  
Table of TI-80 Functions and Instructions.......... A-2  
Menu Map ....................................... A-20  
TI-80 Variables................................... A-26  
Tables and Reference Information A-1  
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Table of TI-80 Functions and Instructions  
A function (F) returns a value or a list and can be used in expressions; an  
instruction (I) initiates an action. Some, but not all, have arguments. † indicates  
that the instruction is available for copying only from the program editor.  
aÀbºc  
Sets the display format for 3  
fraction results to  
aÀbºc (mixed fraction)  
mode. (I)  
áaÀbºcâ  
1-11  
3-9  
valueaÀbºc  
ABS value  
ABS list  
Returns value as a mixed  
fraction. (F)  
J
á4aÀbºcâ  
Returns the absolute value 2 P  
of value. (F)  
2-6  
Returns a list of absolute 2 P  
values for each element in  
list. (F)  
2-6  
Addition: valueA+valueB  
Returns valueA plus  
«
valueB. (F)  
2-4  
Addition: value+list  
Returns a list in which  
value is added to each list  
element. (F)  
«
2-4  
2-4  
Addition: listA+listB  
AUTOSIMP  
bºc  
Returns a list of listA  
elements plus listB  
elements. (F)  
«
Turns on automatic  
simplification mode for  
fractions. (I)  
3  
áAUTOSIMPâ  
1-11  
Sets the display format for 3  
fraction results to  
bºc (simple fraction)  
mode. (I)  
ábºcâ  
1-11  
value8bºc  
Returns value as a simple  
J
fraction. (F)  
á4bºcâ  
3-9  
CLRDRAW  
Deletes all drawn  
elements from a graph or  
drawing. (I)  
2 F DRAW  
áCLRDRAWâ  
7-12  
10-13  
9-13  
CLRHOME  
CLRLIST  
Clears the Home screen.  
(I)  
K I/O  
áCLRHOMEâ  
Deletes  
A EDIT  
áCLRLISTâ  
listnameA,listnameB, . . . listnameA,listnameB, . . .  
(I)  
A-2 Tables and Reference Information  
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CONNECTED  
COS value  
COS list  
Sets connected line  
graphing format. (I)  
3  
áCONNECTEDâ  
1-11  
Returns the cosine of  
value. (F)  
X
X
2-4  
Returns a list of the  
cosine for each list  
element. (F)  
2-4  
COSê value  
Returns the arccosine of 2 R  
value. (F)  
2-4  
COSê list  
Returns a list of the  
arccosine for each list  
element. (F)  
2 R  
2-4  
2-8  
2-8  
2-8  
Cube: valueò  
Returns the cube of value. I MATH  
(F)  
áòâ  
Returns a list of the cube I MATH  
Cube: listò  
for each list element. (F)  
áòâ  
Cube Root: òvalue  
Cube Root: òlist  
Returns the cube root of  
I MATH  
value. (F)  
áòâ  
Returns a list of the cube I MATH  
root for each list element.  
áòâ  
(F)  
2-8  
2-8  
value8DEC  
Returns value in decimal I MATH  
form. (I)  
á4DECâ  
list8DEC  
Returns list in decimal  
I MATH  
form. (I)  
á4DECâ  
2-8  
DEGREE  
Sets degree mode. (I)  
3  
áDEGREEâ  
1-11  
2-14  
8-7  
Degree Notation: value¡  
DIM list  
Interprets value as an  
angle in degrees. (F)  
2 E  
áóâ  
Returns the length of list. 2 = OPS  
(F)  
áDIMâ  
Creates (if necessary) or 2 = OPS  
length!DIM listname  
redimensions list to  
áDIMâ  
length. (I)  
8-7  
10-13  
10-13  
10-13  
10-13  
DISP  
Displays the Home screen. K I/O  
(I)  
áDISPâ  
DISP "text"  
Displays text. (I)  
K I/O  
áDISPâ  
DISP valueA,valueB, . . .  
Displays valueA,  
valueB, . . . (I)  
K I/O  
áDISPâ  
DISP "text",valueA,  
"text",valueB, . . .  
Displays text,valueA,text K I/O  
valueB, . . . (I) áDISPâ  
Tables and Reference Information A-3  
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DISPGRAPH  
Displays the current  
K I/O  
graph. (I)  
áDISPGRAPHâ  
10-13  
2-4  
Division: valueAàvalueB  
Division: listàvalue  
Division: valueàlist  
Division: listAàlistB  
Returns valueA divided by e  
valueB. (F)  
Returns list elements  
divided by value. (F)  
e
e
e
2-4  
Returns value divided by  
list elements. (F)  
2-4  
Returns listA elements  
divided by listB elements.  
(F)  
2-4  
1-11  
7-6  
DOT  
Sets dot graphing format. 3  
(I)  
áDOTâ  
DRAWF expression  
e^power  
Draws expression (in X)  
on the current graph. (I)  
2 F DRAW  
áDRAWFâ  
Returns e raised to the  
value of power. (F)  
2 s  
2 s  
2-5  
e^list  
Returns a list of e raised  
to the power of each list  
element. (F)  
2-5  
ELSE  
See IF:THEN:ELSE  
END  
Identifies the end of a  
FOR(, IF-THEN, or IF-  
THEN-ELSE structure. (I)  
K CTL  
áENDâ  
10-9  
Equal: valueA=valueB  
Equal: listA=listB  
Returns 1 if valueA =  
valueB. Returns 0 if  
valueA ƒ valueB. (F)  
2 D  
á=â  
2-16  
Applies the = test to each 2 D  
element of listA and listB  
á=â  
and returns a list. (F)  
2-16  
Equal: list=value or  
Applies the = test to each 2 D  
value=list  
element of list and value  
á=â  
and returns a list. (F)  
2-16  
1-7  
Exponent: íexponent  
Returns 10 to the  
exponent. (F)  
2 ^  
Exponent: valueíexponent Returns value times 10 to 2 ^  
the exponent. (F)  
1-7  
Exponent: listíexponent  
Returns list elements  
times 10 to the exponent.  
(F)  
2 ^  
1-7  
A-4 Tables and Reference Information  
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EXPREG  
Xlistname,Ylistname  
Fits Xlistname and  
Ylistname to the  
A CALC  
áEXPREGâ  
exponential model. (I)  
9-16  
EXPREG  
Xlistname,Ylistname,  
freqlistname  
Fits Xlistname and  
Ylistname to the  
exponential model  
with frequency  
A CALC  
áEXPREGâ  
freqlistname. (I)  
9-16  
Factorial: value!  
Returns the factorial of  
value (0  integer  69).  
(F)  
I PRB  
á!â  
2-13  
Factorial: list!  
Returns a list containing  
the factorial for each list  
element (0 integers ≤  
69). (F)  
I PRB  
á!â  
2-13  
FIX n  
Sets fixed-decimal display 3  
mode for n decimal  
áFIXâ  
places. (I)  
1-10  
1-10  
4-8  
FLOAT  
FNOFF  
Sets floating-decimal  
display mode. (I)  
3  
áFLOATâ  
Deselects all Y= functions. 2 G ON/OFF  
(I)  
áFNOFFâ  
FNOFF function#,  
Deselects function#,  
2 G ON/OFF  
function#, . . .  
function#, . . . (I)  
áFNOFFâ  
4-8  
FNON  
Selects all Y= functions.  
2 G ON/OFF  
(I)  
áFNONâ  
4-8  
FNON function#,  
Selects function#,  
2 G ON/OFF  
function#, . . . (I)  
áFNONâ  
4-8  
function#, . . .  
FOR(variable,begin,end)  
:commands . . .  
:END  
Executes commands  
through END,  
incrementing variable  
from begin by 1 until  
variable > end. (I)  
K CTL  
áFOR(â  
10-9  
FOR(variable,begin,end,  
increment)  
Executes commands  
through END,  
K CTL  
áFOR(â  
:commands . . .  
:END  
incrementing variable  
from begin by increment  
until variable > end. (I)  
10-9  
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FPART value  
Returns the fractional part I NUM  
of value. (F)  
áFPARTâ  
2-10  
FPART list  
Returns a list of the  
fractional parts for each  
list element. (F)  
I NUM  
áFPARTâ  
2-10  
value8FRAC  
Returns value in fraction  
form, according to the  
current fraction display  
format. (I)  
J
á4FRACâ  
3-10  
list8FRAC  
Displays list in fraction  
form, according to the  
current fraction display  
format. (I)  
J
á4FRACâ  
3-10  
1-11  
FUNC  
Sets function graphing  
mode. (I)  
3  
áFUNCâ  
GOTO label  
Branches the program to K CTL  
label. (I)  
áGOTOâ  
10-10  
Greater Than:  
valueA>valueB  
Returns 1 if valueA >  
valueB. Returns 0 if  
valueA  valueB. (F)  
2 D  
á>â  
2-16  
2-16  
2-16  
2-16  
2-16  
Greater Than:  
listA>listB  
Applies the > test to each 2 D  
element of listA and listB  
á>â  
and returns a list. (F)  
Greater Than:  
list>value or  
value>list  
Applies the > test to each 2 D  
element of list and value  
á>â  
and returns a list. (F)  
Greater Than or Equal:  
valueAvalueB  
Returns 1 if valueA ‚  
valueB. Returns 0 if  
valueA < valueB. (F)  
2 D  
áâ  
Greater Than or Equal:  
listAlistB  
Applies the test to each 2 D  
element of listA and listB  
áâ  
and returns a list. (F)  
Greater Than or Equal:  
listvalue or  
Applies the test to each 2 D  
element of list and value  
áâ  
valuelist  
and returns a list. (F)  
2-16  
4-11  
4-11  
GRIDOFF  
GRIDON  
Turns the graph grid off.  
(I)  
2 F DRAW  
áGRIDOFFâ  
Turns the graph grid on.  
(I)  
2 F DRAW  
áGRIDONâ  
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HORIZONTAL Y  
Draws a horizontal line at 2 F DRAW  
value Y. (I)  
áHORIZONTALâ  
7-5  
IF condition:commandA  
If condition = 0 (false),  
K CTL  
:commands  
skips commandA. (I)  
áIFâ  
10-7  
IF condition  
:THEN:commands  
:END  
Executes commands from † K CTL  
THEN to END if condition  
áTHENâ  
= 1 (true). (I)  
10-8  
IF condition  
:THEN:commands  
:ELSE:commands  
:END  
Executes commands from † K CTL  
THEN to ELSE if  
áELSEâ  
condition = 1 (true); from  
ELSE to END if condition  
= 0 (false). (I)  
10-8  
INPUT  
Displays the current graph K I/O  
with the free-moving  
áINPUTâ  
cursor. (I)  
10-11  
INPUT variable  
Prompts for input to store K I/O  
to variable. (I)  
áINPUTâ  
10-12  
INPUT "text",variable  
Prompts using text and  
stores input to variable.  
(I)  
K I/O  
áINPUTâ  
10-12  
2-10  
2-10  
INT value  
Returns the largest integer I NUM  
 value. (F) áINTâ  
Returns the largest integer I NUM  
INT list  
 list element. (F)  
áINTâ  
integerA INT÷ integerB  
Divides integerA by  
I MATH  
integerB and returns a  
quotient (Q) and  
áINT÷â  
remainder (R) on the  
Home screen, if there are  
no pending operations. (F)  
2-7  
2-7  
2-7  
2-4  
2-4  
listA INT÷ listB  
Returns a list of quotients I MATH  
from listA and listB. (F)  
áINT÷â  
list INT÷ integer or  
integer INT÷ list  
Returns list of quotients  
from integer and list. (F)  
I MATH  
áINT÷â  
Inverse: valueê  
Returns 1 divided by  
value. (F)  
V
V
Inverse: listê  
Returns 1 divided by each  
list element. (F)  
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IPART value  
Returns the integer part of I NUM  
value. (F)  
áIPARTâ  
2-10  
IPART list  
Returns a list of the  
integer part for each list  
element. (F)  
I NUM  
áIPARTâ  
2-10  
LBL label  
Assigns label to the  
K CTL  
command. (I)  
áLBLâ  
10-10  
Less Than: valueA<valueB  
Returns 1 if valueA <  
valueB. Returns 0 if  
valueA valueB. (F)  
2 D  
á<â  
2-16  
2-16  
2-16  
2-16  
2-16  
Less Than: listA<listB  
Applies the < test to each 2 D  
element of listA and listB  
á<â  
and returns a list. (F)  
Less Than: list<value or  
value<list  
Applies the < test to each 2 D  
element of list and value  
á<â  
and returns a list. (F)  
Less Than or Equal:  
valueAvalueB  
Returns 1 if valueA   
valueB. Returns 0 if  
valueA > valueB. (F)  
2 D  
áâ  
Less Than or Equal:  
listAlistB  
Applies the  test to each 2 D  
element of listA and listB  
áâ  
and returns a list. (F)  
Less Than or Equal:  
listvalue or  
Applies the  test to each 2 D  
element of list and value  
áâ  
valuelist  
and returns a list. (F)  
2-16  
LINE(X1,Y1,X2,Y2)  
Draws line from (X1,Y1) 2 F DRAW  
to (X2,Y2). (I)  
áLINE(â  
7-4  
LINREG(a+bX)  
Xlistname,Ylistname  
LINREG(aX+b)  
Fits Xlistname and  
Ylistname to the linear  
model. (I)  
A CALC  
áLINREG(a+bX)â  
áLINREG(aX+b)â  
9-16  
9-15  
Xlistname,Ylistname  
LINREG(a+bX)  
Xlistname,Ylistname,  
freqlistname  
Fits Xlistname and  
Ylistname to the linear  
model with frequency  
freqlistname. (I)  
A CALC  
áLINREG(a+bX)â  
áLINREG(aX+b)â  
9-16  
9-15  
LINREG(aX+b)  
Xlistname,Ylistname,  
freqlistname  
LN value  
Returns the natural  
logarithm of value. (F)  
x
x
2-5  
LN list  
Returns a list of the  
natural logarithm for each  
list element. (F)  
2-5  
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LNREG  
Xlistname,Ylistname  
Fits Xlistname and  
Ylistname to the  
A CALC  
áLNREGâ  
logarithmic model. (I)  
9-16  
LNREG  
Xlistname,Ylistname,  
freqlistname  
Fits Xlistname and  
Ylistname to the  
logarithmic model with  
frequency freqlistname.  
(I)  
A CALC  
áLNREGâ  
9-16  
2-5  
LOG value  
Returns the logarithm of  
value. (F)  
l
l
LOG list  
Returns a list of the  
logarithm for each list  
element. (F)  
2-5  
MANSIMP  
Selects manual  
3  
simplification mode for  
fractions. (I)  
áMANSIMPâ  
1-11  
8-9  
MAX(valueA,valueB)  
MAX(list)  
Returns the larger of  
valueA and valueB. (F)  
2 = MATH  
áMAX(â  
Returns the largest  
2 = MATH  
element in list. (F)  
áMAX(â  
8-9  
MAX(listA,listB)  
Returns a list of the larger 2 = MATH  
of each pair of elements in áMAX(â  
listA and listB. (F)  
8-9  
MAX(list,value) or  
Returns a list of the larger 2 = MATH  
MAX(value,list)  
of each list element  
áMAX(â  
compared to value. (F)  
8-9  
8-9  
8-9  
MEAN(list)  
Returns the mean of list. 2 = MATH  
(F)  
áMEAN(â  
MEAN(list,frequency)  
Returns the mean of list  
with frequency frequency.  
(F)  
2 = MATH  
áMEAN(â  
MEDIAN(list)  
Returns the median of  
2 = MATH  
list. (F)  
áMEDIAN(â  
8-9  
MEDIAN(list,frequency)  
Returns the median of list 2 = MATH  
with frequency frequency.  
áMEDIAN(â  
(F)  
8-9  
8-9  
8-9  
MIN(valueA,valueB)  
Returns the smaller of  
valueA and valueB. (F)  
2 = MATH  
áMIN(â  
MIN(list)  
Returns the smallest  
element in list. (F)  
2 = MATH  
áMIN(â  
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MIN(listA,listB)  
Returns a list of the  
smaller of each pair of  
elements in listA and  
listB. (F)  
2 = MATH  
áMIN(â  
8-9  
MIN(list,value) or  
MIN(value,list)  
Returns a list of the  
smaller of each list  
element compared to  
value. (F)  
2 = MATH  
áMIN(â  
8-9  
Multiplication:  
valueA×valueB  
Returns valueA times  
valueB. (F)  
p
p
2-4  
Multiplication:  
value×list or list×value  
Returns a list containing  
each value times each list  
element. (F)  
2-4  
Multiplication:  
listA×listB  
Returns a list of listA  
elements times listB  
elements. (F)  
p
2-4  
valueA nCr valueB  
Returns the combinations I PRB  
of valueA (integer 0)  
taken valueB (integer 0)  
at a time. (F)  
ánCrâ  
2-13  
2-13  
2-13  
value nCr list  
Returns a list of the  
combinations of value  
(integer 0) taken each  
element in list (integer ‚  
0) at a time. (F)  
I PRB  
ánCrâ  
list nCr value  
Returns a list of the  
combinations of each  
element (integer 0) in list  
taken value (integer 0)  
at a time. (F)  
I PRB  
ánCrâ  
listA nCr listB  
Returns a list of the  
combinations of each  
element (integer 0) in  
listA taken each element  
in listB (integer 0) at a  
time. (F)  
I PRB  
ánCrâ  
2-13  
2-9  
NDERIV(expression,  
variable,value)  
Returns the approximate I MATH  
numerical derivative of  
expression with respect  
to variable at value. ε is  
1íL3. (F)  
áNDERIV(â  
NDERIV(expression,  
Returns the approximate I MATH  
variable,value,ε)  
numerical derivative of  
expression with respect  
to variable at value, with  
a specified ε. (F)  
áNDERIV(â  
2-9  
A-10 Tables and Reference Information  
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Negation: ëvalue  
Negation: ëlist  
Returns the negative of  
value. (F)  
·
·
2-6  
2-6  
Returns a list with each  
list element negated. (F)  
NORMAL  
Sets normal display mode. 3  
(I)  
áNORMALâ  
1-10  
Not Equal: valueAƒvalueB  
Returns 1 if valueA ƒ  
valueB. Returns 0 if  
valueA = valueB. (F)  
2 D  
áƒâ  
2-16  
2-16  
2-16  
Not Equal: listAƒlistB  
Applies the ƒ test to each 2 D  
element of listA and listB  
áƒâ  
and returns a list. (F)  
Not Equal: listƒvalue or  
valueƒlist  
Applies the ƒ test to each 2 D  
element of list and value  
áƒâ  
and returns a list. (F)  
valueA nPr valueB  
Returns a list of the  
I PRB  
permutations of valueA  
(integer 0) taken valueB  
(integer 0) at a time. (F)  
Returns a list of the  
permutations of value  
(integer 0) taken each  
element in list (integer ≥  
0) at a time. (F)  
ánPrâ  
2-13  
2-13  
2-13  
value nPr list  
I PRB  
ánPrâ  
list nPr value  
Returns a list of the  
permutations of each  
element (integer 0) in list  
taken value (integer 0)  
at a time. (F)  
I PRB  
ánPrâ  
listA nPr listB  
Returns a list of the  
permutations of each  
element (integer 0) in  
listA taken each element  
in listB (integer 0) at a  
time. (F)  
I PRB  
ánPrâ  
2-13  
1-VAR STATS listname  
Performs one-variable  
analysis using listname  
and a frequency of 1. (I)  
A CALC  
á1-VAR STATSâ  
9-15  
1-VAR STATS Xlistname,  
freqlistname  
Performs one-variable  
analysis using Xlistname  
and frequency  
A CALC  
á1-VAR STATSâ  
freqlistname. (I)  
9-15  
PARAM  
Sets parametric graphing 3  
mode.  
áPARAMâ  
1-11  
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PAUSE  
Suspends execution of the K CTL  
program until ¸ is  
áPAUSEâ  
pressed. (I)  
10-9  
Pi  
Returns the value of π  
rounded to 13 digits. (F)  
2 T  
2-6  
PLOTn(type,Xlist,Ylist)  
Plots stat plot n (1-3) of  
type (¼ or ½) for Xlist  
and Ylist coordinate pairs.  
2 "  
áPLOTnâ  
9-20  
PLOTn(type,Xlist,Ylist,  
mark)  
Plots stat plot n (1-3) of  
type (¼ or ½) for Xlist  
and Ylist coordinate pairs  
with the specified type of  
mark. (I)  
2 "  
áPLOTnâ  
9-20  
PLOTn(type, Xlist) or  
PLOTn(type,Xlist,Flist)  
Plots stat plot n (1-3) of  
type (¾ or ¿,) for Xlist  
with frequency Flist. If  
Flist is omitted, frequency  
= 1. (I)  
2 "  
áPLOTnâ  
9-20  
9-21  
9-21  
9-21  
9-21  
2-5  
PLOTSOFF  
Deselects all stat plots. (I) 2 "  
áPLOTSOFFâ  
PLOTSOFF plot#,plot# . . .  
PLOTSON  
Deselects stat plot1, plot2, 2 "  
or plot3. (I)  
áPLOTSOFFâ  
Selects all stat plots. (I)  
2 "  
áPLOTSONâ  
PLOTSON plot#,plot# . . .  
Power: value^power  
Power: list^power  
Selects stat plot1, plot2, or 2 "  
plot3. (I)  
áPLOTSONâ  
Returns value raised to  
Z
power. (F)  
Returns a list of each  
element raised to the  
value of power. (F)  
Z
Z
2-5  
Power: value^list  
Returns a list of value  
raised to the power of  
each list element. (F)  
2-5  
Power: listA^listB  
Returns a list of each listA Z  
element raised to the  
power of each listB  
element. (F)  
2-5  
Power of ten: 10^power  
Returns 10 raised to the  
2 h  
value of power. (F)  
2-5  
Power of ten: 10^list  
Returns a list of 10 raised 2 h  
to the power of each list  
element. (F)  
2-5  
A-12 Tables and Reference Information  
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PRGM_programname  
PROD list  
Executes the program  
programname. (I)  
K CTRL  
áPRGM_(â  
10-10  
Returns the product of  
2 = MATH  
elements in list. (F)  
áPRODâ  
8-10  
P8Rx(R,q)  
Returns the rectangular  
coordinate x, given the  
polar coordinates R and q.  
(F)  
2 E  
áP4Ry(â  
2-15  
P8Rx(Rlist,q)  
Returns a list of x  
2 E  
áP4Ry(â  
coordinates, given the R  
coordinates in Rlist and a  
single q. (F)  
2-15  
P8Rx(R,qlist)  
Returns a list of x  
coordinates, given the  
single R coordinate and  
the q coordinates in  
qlist. (F)  
2 E  
áP4Ry(â  
2-15  
P8Rx(Rlist,qlist)  
Returns a list of x  
2 E  
áP4Ry(â  
coordinates, given the R  
and q coordinates in Rlist  
and qlist. (F)  
2-15  
P8Ry(R,q)  
Returns rectangular  
coordinate y, given polar  
coordinates R and q. (F)  
2 E  
áP4Ry(â  
2-15  
P8Ry(Rlist,q)  
Returns a list of y  
2 E  
áP4Ry(â  
coordinates, given the R  
coordinates in Rlist and a  
single q coordinate. (F)  
2-15  
P8Ry(R,qlist)  
Returns a list of y  
2 E  
coordinates, given a single áP4Ry(â  
R coordinate and the q  
coordinates in  
qlist. (F)  
2-15  
P8Ry(Rlist,qlist)  
Returns a list of y  
coordinates, given the R  
coordinates in Rlist and  
the q coordinates in  
qlist. (F)  
2 E  
áP4Ry(â  
2-15  
7-10  
7-10  
7-10  
PT-CHANGE(X,Y)  
PT-OFF(X,Y)  
Toggles the point at (X,Y). 2 F POINTS  
(I)  
Erases the point at (X,Y). 2 F POINTS  
(I)  
áPT-OFF(â  
Draws the point at (X,Y). 2 F POINTS  
(I)  
áPT-CHANGE(â  
PT-ON(X,Y)  
áPT-ON(â  
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PWRREG Xlistname,  
Ylistname  
Fits Xlistname and  
Ylistname to the power  
model. (I)  
A CALC  
áPWRREGâ  
9-16  
PWRREG Xlistname,  
Ylistname,freqlistname  
Fits Xlistname and  
Ylistname to the power  
model with frequency  
freqlistname. (I)  
A CALC  
áPWRREGâ  
9-16  
QUADREG Xlistname,  
Ylistname  
Fits Xlistname and  
Ylistname to the  
A CALC  
áQUADREGâ  
quadratic model. (I)  
9-16  
QUADREG Xlistname,  
Ylistname,freqlistname  
Fits Xlistname and  
Ylistname to the  
quadratic model with  
frequency freqlistname.  
(I)  
A CALC  
áQUADREGâ  
9-16  
1-11  
2-14  
2-12  
RADIAN  
Sets radian mode. (I)  
3  
áRADIANâ  
Radian Notation: valuer  
RAND  
Interprets value as an  
angle in radians.  
2 E  
á r â  
Returns a random number I PRB  
between 0 and 1. (F) áRANDâ  
Returns a random integer I PRB  
RANDINT(lower,  
upper)  
between lower and upper.  
áRANDINT(â  
(F)  
2-13  
2-13  
2-13  
RANDINT(lowerlist,upper)  
Returns a list of random  
integers between each  
element of lowerlist and  
upper. (F)  
I PRB  
áRANDINT(â  
RANDINT(lower,upperlist)  
Returns a list of random  
integers between lower  
and each element of  
upperlist. (F)  
I PRB  
áRANDINT(â  
RANDINT(lowerlist,  
upperlist)  
Returns a list of random  
integers between each  
element of lowerlist and  
upperlist. (F)  
I PRB  
áRANDINT(â  
2-13  
REMAINDER(valueA,  
valueB)  
Returns the remainder  
from the division of  
valueA by valueB  
I NUM  
áREMAINDER(â  
2-11  
REMAINDER(value,  
Returns a list of  
I NUM  
list)  
remainders from the  
division of value by each  
element in list.  
áREMAINDER(â  
2-11  
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REMAINDER(list,  
Returns a list of  
I NUM  
value)  
remainders from the  
division of each element  
in list by value.  
áREMAINDER(â  
2-11  
REMAINDER(listA,  
Returns a list of  
I NUM  
listB)  
remainders from the  
division of each element  
in listA by the each  
element in listB.  
áREMAINDER(â  
2-11  
10-10  
2-8  
Return  
Returns to the calling  
program. (I)  
K CTL  
áRETURNâ  
nthrootxvalue  
nthrootxlist  
Returns nthroot of value. I MATH  
(F)  
áx‡â  
Returns a list of nthroot  
I MATH  
for each list element. (F)  
áxâ  
2-8  
listxvalue  
Returns list roots of  
I MATH  
value. (F)  
áxâ  
2-8  
listAxlistB  
Returns a list of listA  
I MATH  
roots of listB. (F)  
áxâ  
2-8  
ROUND(value)  
ROUND(value,#decimals)  
ROUND(list)  
Returns value rounded to I NUM  
10 digits. (F)  
Returns value rounded to I NUM  
áROUND(â  
2-10  
2-10  
2-10  
#decimals ( 9). (F)  
áROUND(â  
Returns list elements  
I NUM  
rounded to 10 digits. (F)  
áROUND(â  
ROUND(list,#decimals)  
Returns list elements  
rounded to #decimals  
( 9). (F)  
I NUM  
áROUND(â  
2-10  
2-15  
2-15  
2-15  
R8Pr(X,Y)  
Returns the polar  
coordinate r, given the  
rectangular coordinates X  
and Y. (F)  
2 E  
áR4Pq(â  
R8Pr(Xlist,Y)  
R8Pr(X,Ylist)  
Returns a list of r  
2 E  
áR4Pq(â  
coordinates, given the X  
coordinates in Xlist and a  
single Y coordinate. (F)  
Returns a list of r  
coordinates, given a single áR4Pq(â  
X coordinate and the Y  
2 E  
coordinates in Ylist. (F)  
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R8Pr(Xlist,Ylist)  
Returns a list of r  
coordinates, given the X  
coordinates in Xlist and  
the Y coordinates in Ylist.  
(F)  
2 E  
áR4Pq(â  
2-15  
2-15  
2-15  
2-15  
R8Pq(X,Y)  
Returns the polar  
coordinate q, given the  
rectangular coordinates X  
and Y. (F)  
2 E  
áR4Pq(â  
R8Pq(Xlist,Y)  
R8Pq(X,Ylist)  
R8Pq(Xlist,Ylist)  
Returns a list of q  
2 E  
áR4Pq(â  
coordinates, given the X  
coordinates in Xlist and a  
single Y coordinate. (F)  
Returns a list of q  
coordinates, given a single áR4Pq(â  
X coordinate and the Y  
2 E  
coordinates in Ylist. (F)  
Returns a list of q  
coordinates, given the X  
coordinates in Xlist and  
the Y coordinates in Ylist.  
(F)  
2 E  
áR4Pq(â  
2-15  
SCI  
Sets scientific display  
3  
mode. (I)  
áSCIâ  
1-10  
seq(expression,variable,  
begin,end,increment)  
Returns a list created by  
evaluating expression for  
variable, from begin to  
end by increment. (F)  
y ãLISTä OPS  
áseq(â  
8-8  
sequential  
Sets sequential graphing  
3  
mode. (F)  
ásequentialâ  
1-11  
SHADE(lowerfunc,  
upperfunc)  
Shades the area above  
lowerfunc and below  
upperfunc. (I)  
2 F DRAW  
áSHADE(â  
7-9  
SHADE(lowerfunc,  
upperfunc,resolution)  
Shades the area above  
lowerfunc, below  
upperfunc, and with  
resolution (1 through 9).  
(I)  
2 F DRAW  
áSHADE(â  
7-9  
SHADE(lowerfunc,  
upperfunc,resolution,  
Xleft)  
Shades the area above  
lowerfunc, below  
upperfunc, to right of  
X=Xleft, and with  
resolution (1 through 9).  
(I)  
2 F DRAW  
áSHADE(â  
7-9  
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SHADE(lowerfunc,  
upperfunc,resolution,  
Xleft,Xright)  
Shades the area above  
lowerfunc, below  
upperfunc, to right of  
X=Xleft, to left of  
X=Xright, and with  
resolution (1 through 9).  
(I)  
2 F DRAW  
áSHADE(â  
7-9  
SHADE_Y>func1,func2, . . . Shades the area above  
func1 with vertical  
2 F DRAW  
áSHADE_Y>â  
pattern and above func2  
with diagonal pattern  
(lower left to upper right),  
etc. (I)  
7-7  
SHADE_Y<func3,func4, . . . Shades the area below  
func3 with horizontal  
2 F DRAW  
áSHADE_Y<â  
pattern and below func4  
with diagonal pattern  
(upper left to lower right),  
etc. (I)  
7-8  
fractionúSIMP  
Simplifies fraction by its  
J
lowest common factor. (F) áSIMPâ  
3-8  
(fraction,factor)úSIMP  
Simplifies fraction by the  
specified factor, which  
must be an integer. (F)  
J
áSIMPâ  
3-8  
1-11  
2-4  
SIMUL  
Sets simultaneous  
graphing mode. (I)  
3  
áSIMULâ  
SIN value  
SIN list  
Returns the sine of value.  
(F)  
W
Returns a list of the sine  
W
for each list element. (F)  
2-4  
SINê value  
SINê list  
Returns the arcsine of  
value. (F)  
2 ãSIN1ä  
2 ãSIN1ä  
2-4  
Returns a list of the  
arcsine for each list  
element. (F)  
2-4  
SORTA(listname)  
Sorts listname elements  
2 = OPS  
in ascending order. (I)  
áSORTA(â  
8-6  
SORTA(keylistname,  
dependlist1,  
dependlist2, . . .)  
Sorts the elements of  
keylistname in ascending  
order with dependlist1,  
dependlist2 . . . as  
2 = OPS  
áSORTA(â  
dependent lists. (I)  
8-6  
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SORTD(listname)  
Sorts the elements of  
listname in descending  
order. (I)  
2 = OPS  
áSORTD(â  
8-6  
SORTD(keylistname,  
dependlist1,  
Sorts the elements of  
keylistname in  
2 = OPS  
áSORTD(â  
dependlist2, . . .)  
descending order with  
dependlist1,  
dependlist2 . . . as  
dependent lists. (I)  
8-6  
2-5  
2-5  
2-5  
Square: valueñ  
Returns value multiplied  
by itself. (F)  
a
a
Square: listñ  
Returns a list of each list  
element squared. (F)  
Square Root: value  
Square Root: list  
Returns the square root of 2 ]  
value. (F)  
Returns a list of the  
square roots of each list  
element. (F)  
2 ]  
2-5  
STOP  
Stops program execution K CTL  
and returns to the Home  
áSTOPâ  
screen. (I)  
10-10  
Store: value!variable  
Stores value to variable.  
§
(I)  
1-13  
Store: list!listname  
Stores list to listname. (I)  
§
§
1-13  
Store:  
Stores expression to Yn  
"expression"!Yn or  
"expression"!XnT or  
"expression"!YnT  
XnT or YnT function. (I)  
1-13  
Subtraction:  
valueAìvalueB  
Subtracts valueB from  
valueA. (F)  
|
|
2-4  
Subtraction:  
valueìlist  
Subtracts list elements  
from value and returns a  
list. (F)  
2-4  
Subtraction:  
listìvalue  
Subtracts value from list  
elements and returns a  
list. (F)  
|
|
2-4  
Subtraction:  
listAìlistB  
Subtracts each listB  
element from each listA  
element and returns a list.  
(F)  
2-4  
8-10  
2-4  
SUM list  
Returns the sum of  
elements in list. (F)  
2 = MATH  
áSUMâ  
TAN value  
Returns the tangent of  
value. (F)  
Y
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TAN list  
Returns a list of the  
tangent for each list  
element. (F)  
Y
2-4  
TANê value  
Returns the arctangent of 2 S  
value. (F)  
2-4  
TANê list  
Returns a list of the  
arctangent for each list  
element. (F)  
2 S  
2-4  
THEN  
See IF:THEN  
TRACE  
Displays a graph and  
+  
enters Trace mode. (I)  
4-13  
2-VAR STATS  
Xlistname,Ylistname  
Performs two-variable  
analysis using Xlistname  
and Ylistname. (I)  
A CALC  
á2-VAR STATSâ  
9-15  
2-VAR STATS  
Xlistname,Ylistname,  
freqlistname  
Performs two-variable  
analysis using Xlistname  
and Ylistname with  
frequency freqlistname.  
(I)  
A CALC  
á2-VAR STATSâ  
9-15  
VERTICAL X  
Draws a vertical line at  
2 F DRAW  
value X. (I)  
áVERTICALâ  
7-5  
ZBOX  
Displays a graph to allow *  
the user to define new  
áZBOXâ  
viewing window. (I)  
4-15  
4-17  
4-16  
4-16  
4-17  
4-17  
4-17  
ZDECIMAL  
ZOOM IN  
Displays a graph in new  
viewing window. (I)  
*  
áZDECIMALâ  
Displays a graph in new  
viewing window. (I)  
*  
áZOOM INâ  
ZOOM OUT  
ZSQUARE  
ZSTANDARD  
ZTRIG  
Displays a graph in new  
viewing window. (I)  
*  
áZOOM OUTâ  
Displays a graph in new  
viewing window. (I)  
*  
áZSQUAREâ  
Displays a graph in new  
viewing window. (I)  
*  
áZSTANDARDâ  
Displays a graph in new  
viewing window. (I)  
*  
áZTRIGâ  
Tables and Reference Information A-19  
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TI-80 Menu Map  
Menus begin in the upper left of the keyboard. Default values are shown.  
(
ÚÁÄÄÄÄÄÄÄÄÄÄÄÄÄÄ¿  
)
ÚÁÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄ¿  
(FUNC mode)  
WINDOW  
(FUNC mode)  
Y1=  
(PARAM mode)  
(PARAM mode)  
WINDOW  
XãT=  
YãT=  
XäT=  
YäT=  
XåT=  
YåT=  
XMIN=ì10  
XMAX=10  
XSCL=1  
YMIN=ì10  
YMAX=10  
YSCL=1  
Y2=  
Y3=  
TMIN=0  
TMAX=2p  
TSTEP=24  
XMIN=ì10  
XMAX=10  
XSCL=1  
Y4=  
YMIN=ì10  
YMAX=10  
YSCL=1  
2 [TblSet]  
ÚÄÄÙ  
TABLE SETUP  
TBLMIN=0  
@TBL=1  
*
ÚÄÙ  
ZOOM  
1:ZBOX  
2:ZOOM IN  
3:ZOOM OUT  
4:ZDECIMAL  
5:ZSQUARE  
6:ZSTANDARD  
7:ZTRIG  
3
ÚÄÙ  
NORMAL SCI  
3 (in program editor)  
ÚÄÙ  
MODE  
FLOAT 0123456789  
RADIAN DEGREE  
aÀbºc bºc  
AUTOSIMP MANSIMP  
FUNC PARAM  
CONNECTED DOT  
SEQUENTIAL SIMUL  
1:NORMAL  
2:SCI  
3:FLOAT  
4:FIX  
5:RADIAN  
6:DEGREE  
7:aÀbºc  
8:bºc  
9:AUTOSIMP  
0:MANSIMP  
A:FUNC  
B:PARAM  
C:CONNECTED  
D:DOT  
E:SEQUENTIAL  
F:SIMUL  
A-20 Tables and Reference Information  
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2 "  
ÚÄÄÄÄÄÙ  
STAT PLOTS  
1:PLOT1...  
OFF ¼ L1 L2 Â  
2:PLOT2...  
OFF ¼ L1 L2 Â  
3:PLOT3...  
2 " (in program editor)  
ÚÄÄÄÄÄÄÁÄÄÄÄÄÄÄÄÂÄÄÄÄÄÄÄÄÄÄ¿  
PLOTS  
TYPE  
1:¼  
2:½  
3:¾  
4:¿  
MARK  
1:Â  
2:+  
3:¦  
1:PLOT1(  
2:PLOT2(  
3:PLOT3(  
4:PLOTSOFF  
5:PLOTSON  
OFF ¼ L1 L2 Â  
4:PLOTSOFF  
5:PLOTSON  
Screen for ¾ or ¿ plots  
(1-variable plots)  
PLOTn  
ON OFF  
TYPE: ¼ ½ ¾ ¿  
XL: L1L2L3L4L5L6  
F: 1L1L2L3L4L5L6  
Screen for ¼ or ½ plots  
(2-variable plots)  
PLOTn  
ON OFF  
TYPE: ¼ ½ ¾ ¿  
XL: L1L2L3L4L5L6  
YL: L1L2L3L4L5L6  
MARK: Â + ¦  
A
ÚÁÄÄÄÄÄÄÄÄÄÄÄÄ¿  
EDIT  
CALC  
1:EDIT...  
2:SORTA(  
3:SORTD(  
4:CLRLIST  
1:1-VAR STATS  
2:2-VAR STATS  
3:LINREG(aX+b)  
4:QUADREG  
5:LINREG(a+bX)  
6:LNREG  
7:EXPREG  
8:PWRREG  
Tables and Reference Information A-21  
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2 =  
ÚÄÄÁÄÄÄÄÄÄÄÄÄ¿  
OPS  
MATH  
1:SORTA(  
2:SORTD(  
3:DIM  
1:MIN(  
2:MAX(  
3:MEAN(  
4:MEDIAN(  
5:SUM  
4:SEQ(  
6:PROD  
I
ÚÁÄÄÄÄÄÄÄÄÄÄÄÄÂÄÄÄÄÄÄÄÄÄÄÄÄÄ¿  
MATH  
NUM  
PRB  
1:INT÷  
1:ROUND(  
2:IPART  
3:FPART  
4:INT  
1:RAND  
2:nPr  
3:nCr  
4:!  
2:4DEC  
3
3:  
3
4: ‡  
X
5: ‡  
5:MIN(  
5:RANDINT(  
6:NDERIV( 6:MAX(  
7:REMAINDER(  
J
ÚÙ  
2 D  
ÚÄÄÄÄÙ  
TEST  
1:=  
2:ƒ  
3:>  
4:‚  
5:<  
6:  
2 E  
ÚÄÄÄÄÙ  
ANGLE  
1:¡  
FRACTION  
1:4SIMP  
2:4bºc  
3:4aÀbºc  
4:4FRAC  
5:4DEC  
r
2:  
3:R4Pr(  
4:R4Pq(  
5:P4Rx(  
6:P4Ry(  
A-22 Tables and Reference Information  
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K
ÚÁÄÄÄÄÄÄÄÄÂÄÄÄÄÄÄÄÄÄ¿  
K (in program editor)  
ÚÁÄÄÄÄÄÄÄÄÂÄÄÄÄÄÄÄÄÄÄÄÄ¿  
EXEC  
EDIT  
NEW  
CTL  
I/O  
EXEC  
1:name 1:name 1:CREATE NEW 1:IF  
1:INPUT  
1:name  
2:name  
2:name 2:name  
2:THEN 2:DISP  
3:name 3:name  
3:ELSE 3:DISPGRAPH 3:name  
©
©
4:FOR( 4:CLRHOME  
5:END  
©
6:PAUSE  
7:LBL  
8:GOTO  
9:PRGM_  
0:RETURN  
A:STOP  
2 F  
ÚÄÄÄÄÁÄÄÄÄÄÄÄÄÄÄ¿  
DRAW  
1:CLRDRAW  
2:LINE(  
POINTS  
1:PT-ON(  
2:PT-OFF(  
3:HORIZONTAL 3:PT-CHANGE(  
4:VERTICAL  
5:DRAWF  
6:SHADE_Y>  
7:SHADE_Y<  
8:SHADE(  
9:GRIDON  
0:GRIDOFF  
Tables and Reference Information A-23  
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L
ÚÄÙ  
VARS  
1:WINDOW...  
2:STATISTICS…  
3:TABLE…  
4:SIMPFACTOR…  
L áWINDOW…â  
L áTABLE…â  
ÚÄÄÄÄÄÄÙ  
TABLE  
ÚÄÄÄÄÄÄÁÄÄÄÄÄ¿  
X/Y  
T
1:XMIN  
2:XMAX  
3:XSCL  
4:YMIN  
5:YMAX  
6:YSCL  
7:@X  
8:@Y  
9:XFACT  
0:YFACT  
1:TMIN  
2:TMAX  
3:TSTEP  
1:TBLMIN  
2:@TBL  
L áSIMPFACTOR…â  
ÚÄÄÄÄÙ  
SIMPFACTOR  
1:FACTOR  
L áSTATISTICS…â  
ÚÄÄÄÄÄÄÁÄÄÂÄÄÄÄÄÄÄÄÄÄÂÄÄÄÄÄÄÄÄÄÄ¿  
X/Y  
1:n  
2:v  
3:Sx  
4:sx  
G
EQ  
1:a  
2:b  
3:c  
4:r  
5:REGEQ  
BOX  
1:GX  
2:GXñ  
3:GY  
4:GYñ  
5:GXY  
1:Qã  
2:MED  
3:Qå  
5:w  
6:Sy  
7:sy  
8:MINX  
9:MAXX  
0:MINY  
A:MAXY  
2 G  
ÚÄÄÄÄÁÄÄÄÄÄÄÄÄÄÂÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄ¿  
Y
XT/YT  
1:XãT  
2:YãT  
3:XäT  
4:YäT  
3:XåT  
4:YåT  
ON/OFF  
1:FNON  
2:FNOFF  
1:Y1  
2:Y2  
3:Y3  
4:Y4  
A-24 Tables and Reference Information  
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2 ¯  
ÚÄÙ  
MEMORY  
1:CHECK RAM…  
2:DELETE…  
3:RESET…  
2 ¯ áCHECK RAM…â 2 ¯ áDELETE…â  
2 ¯ áRESET…â  
ÚÄÄÄÄÄÄÙ  
1:NO  
ÚÄÄÄÄÙ  
MEM FREE 7014  
ÚÄÄÄÄÄÄÙ  
DELETE:  
REAL  
LIST  
Y-VARS  
PRGM  
14  
0
80  
14  
úname memory  
name memory  
name memory  
2:RESET  
Resetting memory  
erases all data and  
programs.  
©
©
(names include defined  
programs, lists, Y=  
equations, and user  
variables, in that order.)  
Tables and Reference Information A-25  
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TI-80 Variables  
The variables listed below are used by the TI-80 in various ways. Some have  
restrictions on their use.  
User Variables  
The variables A through Z and q can hold only numbers—  
either decimals or fractions. You may store to these variables.  
The TI-80 can update X, Y, and T during graphing; therefore,  
you may wish to reserve those variables for graphing  
activities.  
The variables Lã through L6 are defined as lists. You cannot  
store another type of data to them.  
You can store any string of characters, functions, instructions,  
or variable names to the functions Yn (in FUNC mode) and  
Xnî and Ynî (in PARAM mode), by using either § or the  
Y= editor. The validity of the string is determined when the  
function is evaluated.  
System  
Variables  
The values of the Window variables XMIN, XMAX, XSCL,  
@X, TSTEP, etc. must be real numbers. You may store to  
them. Since the TI-80 can update some of them, as the result  
of a Zoom instruction, for example, you may wish to reserve  
these variables for graphing activities.  
The statistical result variables n, v, MINX, GX, a, r, REGEQ,  
X1, Y1, Q1, MED, Q3, etc. are reserved for use by the TI-80.  
You cannot store to them.  
A-26 Tables and Reference Information  
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Appendix B: Service and Warranty Information  
This appendix provides supplemental information that may be helpful as you  
use the TI.80. It includes procedures that may help you correct problems with  
the calculator.  
Appendix  
Contents  
Battery Information ...............................  
Accuracy Information .............................  
B-2  
B-8  
In Case of Difficulty ............................... B-10  
Error Conditions.................................. B-11  
Service and Support Information ................... B-14  
Warranty Information.............................. B-15  
Service and Warranty Information B-1  
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Battery Information  
The TI.80 uses two CR2032 lithium 3-volt batteries.  
When to Replace As you use the TI.80, the battery voltage will gradually drop,  
the Batteries  
and the display will dim. You can adjust the contrast to darken  
the display when this happens. If the display is dim and  
adjusting the contrast to level 9 does not make it dark enough,  
you should replace the batteries. Refer to pages B-3 through  
B-7 for instructions on how to change the batteries.  
Battery  
Follow these safety guidelines concerning batteries.  
Precautions  
¦
¦
¦
¦
¦
Do not mix new and used batteries.  
Do not mix different types of batteries.  
Follow polarity diagrams carefully.  
Do not replace batteries with rechargeable batteries.  
Do not place non-rechargeable batteries in a battery  
charger.  
¦
¦
Properly dispose of used batteries immediately. Do not  
leave them within the reach of small children.  
Do not incinerate used batteries.  
Retaining Stored  
Data  
Caution: The TI-80 retains stored data when you are  
changing batteries only if you:  
¦
Do not remove both batteries at the same time. (At least  
one battery must be installed at all times in order to  
retain memory.)  
¦
¦
Turn the unit off and do not turn it back on until you have  
changed the batteries.  
Do not allow the batteries to run down completely before  
changing them.  
Follow the steps on pages B-3 through B-7 when changing  
batteries.  
B-2 Service and Warranty Information  
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Changing the  
Batteries  
(Continued)  
To change the batteries, first:  
a. Turn the calculator off.  
b. Replace the plastic slide cover over the keys.  
c. Turn the calculator so that the back is facing you.  
Placing your thumb on the ridged area of the plastic battery  
compartment cover, push down slightly and slide the cover to  
the right until you can lift off the cover.  
Push the red switch up to free the metal battery cover over the  
lower battery.  
Service and Warranty Information B-3  
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Changing the  
Batteries  
(Continued)  
Slide the metal battery cover away from the battery. The  
battery pops up.  
Remove the old battery. Insert a new battery, positive side (+)  
up.  
Hold the new battery in place and slide the metal battery  
cover back into position over the battery.  
B-4 Service and Warranty Information  
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Changing the  
Batteries  
(Continued)  
Push the red switch all the way down to free the metal battery  
cover over the upper battery.  
Slide the metal battery cover away from the battery.  
Remove the old battery. Insert a new battery, positive side (+)  
up.  
Service and Warranty Information B-5  
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Changing the  
Batteries  
(Continued)  
Hold the new battery in place and slide the metal battery  
cover back into position over the battery.  
Push the red switch to its center position to lock the metal  
covers and batteries into place.  
Note: The calculator will not turn on unless the red switch is  
in the center position.  
B-6 Service and Warranty Information  
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Changing the  
Batteries  
(Continued)  
Replace the plastic battery compartment cover. Turn the  
calculator on and adjust the contrast display.  
To adjust the display contrast, press and release the 2 key.  
To increase the contrast (darken the screen), press and hold  
7. To decrease the contrast (lighten the screen), press and  
hold 8.  
Service and Warranty Information B-7  
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Accuracy Information  
To maximize accuracy, the TI.80 carries more digits internally than it displays.  
Computational  
Accuracy  
Values in memory are stored using up to 13 digits with a  
two-digit exponent.  
¦
You can store values in the Window variables using up to  
10 digits (13 digits for XSCL, YSCL, and TSTEP).  
¦
When a value is displayed, the displayed value is rounded  
as specified by the MODE setting (Chapter 1), with a  
maximum of 10 digits and a two-digit exponent.  
¦
REGEQ displays up to 13 digits.  
Graphing  
Accuracy  
XMIN is the center of the leftmost pixel, XMAX is the center of  
the next to the rightmost pixel. (The rightmost pixel is  
reserved for the busy indicator.) @X is the distance between  
the centers of two adjacent pixels.  
¦
¦
@X is calculated as (XMAX–XMIN)à62.  
If @X is entered from the Home screen or a program, then  
XMAX is calculated as XMIN+@X×62.  
Ymin is the center of the next to the bottom pixel, YMAX is  
the center of the top pixel. @Y is the distance between the  
centers of two adjacent pixels.  
¦
¦
@Y is calculated as (YMAX.YMIN)à46.  
If @Y is entered from the Home screen or a program, then  
YMAX is calculated as YMIN+@Y×46.  
Cursor coordinates are displayed as six characters, which may  
include a negative sign, decimal point, and exponent.  
B-8 Service and Warranty Information  
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Function  
Limits  
Following is a table of functions and the range of input values  
for each.  
Function  
Input Values  
SIN x, COS x, TAN x  
0  | x | < 1010 (degree)  
1
SIN x, COS 1 x  
-1  x  1  
-
-
-
LN x, LOG x  
ex  
10x  
x  
x!  
10 100 < x < 10100  
-10100 < x  230.2585092993  
-10100 < x < 100  
0  x < 10100  
0  x  69, where x is an integer  
Function Results Following is a table of functions and the range of the result for  
each.  
Function  
Range of Result  
1
SIN x, TAN 1 x  
-90¡ to 90¡ or -pà2 to 2 (radians)  
0¡ to 180¡ or 0 to p (radians)  
-
-
COS 1 x  
-
Service and Warranty Information B-9  
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In Case of Difficulty  
If you have difficulty operating the calculator, the following suggestions may  
help you to correct the problem.  
Handling a  
Difficulty  
Follow these procedures if you have difficulties.  
1. If you cannot see anything on the display, perhaps the  
display contrast needs adjusting.  
Press and release the 2 key. To increase the contrast  
(darken the screen), press and hold 7. To decrease the  
contrast (lighten the screen), press and hold 8.  
You will find additional information on display contrast on  
page 1-3.  
2. If after adjusting the display contrast, the calculator does  
not appear to be working at all, be sure the batteries are  
installed properly and that they are fresh. Refer to “Battery  
Information” beginning on page B-2 for more details.  
Note: Make sure the red switch in the battery  
compartment is in the center position.  
3. If an error occurs, follow the procedure on page 1-22.  
Refer to the more detailed explanations about specific  
errors beginning on page B-11, if necessary.  
4. If the cursor is a checker-board pattern, memory is full.  
Press 2 ¯ DELETE... and delete some items from  
memory. See Chapter 12 for additional information about  
memory management.  
5. If the dotted-line busy indicator is displayed, a graph or  
program is paused, and the TI-80 is waiting for input.  
Press ¸ to continue or ´ to break.  
B-10 Service and Warranty Information  
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Error Conditions  
When the TI.80 detects an error, it displays ERR:message and the error menu.  
The general procedure for correcting errors is described on  
page 1.22. The error messages, their possible causes, and suggestions for  
correction are shown below.  
ARGUMENT  
BREAK  
A function or instruction does not have the correct number of  
arguments. See Appendix A and the appropriate chapter.  
You have pressed the ´ key to break execution of a program,  
halt a Draw instruction, or stop evaluation of an expression.  
DATA TYPE  
You have entered a value or variable that is the wrong data  
type.  
¦
A function (including implied multiplication) or an  
instruction has an argument that is an invalid data type; for  
example, a list where a real number is required. See  
Appendix A and the appropriate chapter.  
¦
¦
You are attempting to store to an incorrect data type; for  
example, a list to a real variable.  
In function graphing or parametric graphing, you have  
generated a list result rather than a single value; for  
example, attempting to graph Yã={1,2,3}×X.  
DIM MISMATCH  
DOMAIN  
You are attempting to perform an operation that uses more  
than one list, but the dimensions do not match.  
Typically, this occurs when the value of an argument does not  
fall within a specified range.  
¦
¦
You are attempting to divide by zero.  
You are attempting a logarithmic or power regression with  
a LX or an exponential or power regression with  
a LY.  
¦
A zero value for ε for NDERIV( will result in this error.  
This error does not occur during graphing because the  
TI-80 allows for undefined values on a graph.  
Service and Warranty Information B-11  
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INCREMENT  
¦
¦
The increment in SEQ( is 0 or has the wrong sign. This  
error does not occur during graphing. The TI-80 allows  
for undefined values on a graph.  
The increment in FOR( is 0 or has the wrong sign.  
INVALID  
You are attempting to reference a variable or use a function  
in a place where it is not valid. For example, Yn cannot  
reference Y, XMIN, @X, or TBLMIN.  
INVALID DIM  
¦
The dimension of the argument is not appropriate for the  
operation.  
¦
List element dimensions must be integers between 1 and  
99; for example, L1(100) will cause an error.  
LABEL  
The label in the GOTO instruction is not defined with a LBL  
instruction in the program.  
MEMORY  
¦
There is insufficient memory in which to perform the  
desired command. You must delete item(s) from memory  
(Chapter 12) before executing this command.  
¦
Using an IF/THEN or FOR( with a GOTO that branches out  
of the loop can also cause this error because the END  
statement that terminates the loop is never reached.  
MODE  
You are attempting a úSIMP in AUTOSIMP mode.  
This error occurs when any nested combination of function  
NEST LEVEL  
evaluation, NDERIV( or SEQ( exceeds 5 levels.  
OVERFLOW  
You are attempting to enter, or you have calculated, a  
number that is beyond the range of the calculator. This error  
does not occur during graphing. The TI-80 allows for  
undefined values on a graph.  
B-12 Service and Warranty Information  
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STAT  
¦
¦
You are attempting a linear regression with a vertical line.  
Statistical analyses must have at least two data points;  
QUADREG must have at least three data points.  
The list of s (frequency) elements must be 0, and at  
least one F value must be 0.  
The frequency list, when used for “sorting” statistics  
(median, Qã, Qå, or boxplot), must be an integer 0 and   
99.  
¦
¦
¦
(XMAX.XMIN)àXSCL must be  31 for a histogram.  
STAT PLOT  
SYNTAX  
You are trying to display a graph when there is a statistical  
plot turned on that uses an undefined list.  
The command contains a syntax error. Look for misplaced  
functions, arguments, parentheses, or commas. See Appendix  
A and the appropriate chapter.  
UNDEFINED  
You are attempting to reference a variable that is not  
currently defined. For example, a statistical variable , which  
has no current value because a list has been edited, has been  
referenced.  
WINDOW RANGE  
There is a problem with the Window variables.  
¦
You may have defined XMAXXMIN, YMAXYMIN,  
TSTEP=0, or TMAXTMIN and TSTEP>0 (or vice versa).  
¦
The Window variables are too small or too large to graph  
correctly. This can occur if you attempt to zoom in or out  
so far that you are not within the numerical range of the  
calculator.  
ZOOM  
A point or a line, rather than a box, is defined in ZBOX; or a  
math error has resulted from a Zoom operation.  
Service and Warranty Information B-13  
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Support and Service Information  
Product Support  
Customers in the U.S., Canada, Puerto Rico, and the Virgin Islands  
For general questions, contact Texas Instruments Customer Support:  
phone:  
e-mail:  
1.800.TI.CARES (1.800.842.2737)  
For technical questions, call the Programming Assistance Group of Customer  
Support:  
phone:  
1.972.917.8324  
Customers outside the U.S., Canada, Puerto Rico, and the Virgin Islands  
Contact TI by e-mail or visit the TI calculator home page on the World Wide Web.  
e-mail:  
Internet:  
Product Service  
Customers in the U.S. and Canada Only  
Always contact Texas Instruments Customer Support before returning a product  
for service.  
Customers outside the U.S. and Canada  
Refer to the leaflet enclosed with this product or contact your local Texas  
Instruments retailer/distributor.  
Other TI Products and Services  
Visit the TI calculator home page on the World Wide Web.  
Refer to the leaflet enclosed with this product or contact your local Texas  
Instruments retailer/distributor.  
B–14 Service and Warranty Information  
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Warranty Information  
Customers in the U.S. and Canada Only  
One-Year Limited Warranty for Electronic Product  
This Texas Instruments (“TI”) electronic product warranty extends only to the original  
purchaser and user of the product.  
Warranty Duration. This TI electronic product is warranted to the original purchaser  
for a period of one (1) year from the original purchase date.  
Warranty Coverage. This TI electronic product is warranted against defective  
materials and construction. THIS WARRANTY IS VOID IF THE PRODUCT HAS BEEN  
DAMAGED BY ACCIDENT OR UNREASONABLE USE, NEGLECT, IMPROPER  
SERVICE, OR OTHER CAUSES NOT ARISING OUT OF DEFECTS IN MATERIALS  
OR CONSTRUCTION.  
Warranty Disclaimers. ANY IMPLIED WARRANTIES ARISING OUT OF THIS SALE,  
INCLUDING BUT NOT LIMITED TO THE IMPLIED WARRANTIES OF  
MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE, ARE LIMITED  
IN DURATION TO THE ABOVE ONE-YEAR PERIOD. TEXAS INSTRUMENTS SHALL  
NOT BE LIABLE FOR LOSS OF USE OF THE PRODUCT OR OTHER INCIDENTAL  
OR CONSEQUENTIAL COSTS, EXPENSES, OR DAMAGES INCURRED BY THE  
CONSUMER OR ANY OTHER USER.  
Some states/provinces do not allow the exclusion or limitation of implied warranties or  
consequential damages, so the above limitations or exclusions may not apply to you.  
Legal Remedies. This warranty gives you specific legal rights, and you may also have  
other rights that vary from state to state or province to province.  
Warranty Performance. During the above one (1) year warranty period, your defective  
product will be either repaired or replaced with a reconditioned model of an equivalent  
quality (at TI’s option) when the product is returned, postage prepaid, to Texas  
Instruments Service Facility. The warranty of the repaired or replacement unit will  
continue for the warranty of the original unit or six (6) months, whichever is longer.  
Other than the postage requirement, no charge will be made for such repair and/or  
replacement. TI strongly recommends that you insure the product for value prior to  
mailing.  
Software. Software is licensed, not sold. TI and its licensors do not warrant that the  
software will be free from errors or meet your specific requirements. All software is  
provided “AS IS.”  
Copyright. The software and any documentation supplied with this product are  
protected by copyright.  
Service and Warranty Information B-15  
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Australia & New Zealand Customers only  
One-Year Limited Warranty for Commercial Electronic Product  
This Texas Instruments electronic product warranty extends only to the  
original purchaser and user of the product.  
Warranty Duration. This Texas Instruments electronic product is warranted  
to the original purchaser for a period of one (1) year from the original  
purchase date.  
Warranty Coverage. This Texas Instruments electronic product is warranted  
against defective materials and construction. This warranty is void if the  
product has been damaged by accident or unreasonable use, neglect, improper  
service, or other causes not arising out of defects in materials or construction.  
Warranty Disclaimers. Any implied warranties arising out of this sale,  
including but not limited to the implied warranties of merchantability  
and fitness for a particular purpose, are limited in duration to the  
above one-year period. Texas Instruments shall not be liable for loss  
of use of the product or other incidental or consequential costs,  
expenses, or damages incurred by the consumer or any other user.  
Some jurisdictions do not allow the exclusion or limitation of implied  
warranties or consequential damages, so the above limitations or exclusions  
may not apply to you.  
Legal Remedies. This warranty gives you specific legal rights, and you may  
also have other rights that vary from jurisdiction to jurisdiction.  
Warranty Performance. During the above one (1) year warranty period,  
your defective product will be either repaired or replaced with a new or  
reconditioned model of an equivalent quality (at TI’s option) when the product  
is returned to the original point of purchase. The repaired or replacement unit  
will continue for the warranty of the original unit or six (6) months, whichever  
is longer. Other than your cost to return the product, no charge will be made  
for such repair and/or replacement. TI strongly recommends that you insure  
the product for value if you mail it.  
Software. Software is licensed, not sold. TI and its licensors do not warrant  
that the software will be free from errors or meet your specific requirements.  
All software is provided “AS IS.”  
Copyright. The software and any documentation supplied with this product  
are protected by copyright.  
All Customers Outside the U.S. and Canada  
For information about the length and terms of the warranty, refer to your package  
and/or to the warranty statement enclosed with this product, or contact your local Texas  
Instruments retailer/distributor.  
B-16 Service and Warranty Information  
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Index  
A
A (Cont.)  
AUTOSIMP MODE, 1-9, 1-11, 3-4, A-2  
Axes (graphing), 4-9  
a variable, 9-15 to 9-17, A-26  
aÀbºc MODE, 1-9, 1-11, 3-4, A-2  
8aÀbºc, 3-8, 3-9, A-2  
ABS, 2-6, A-2  
Absolute value, 2-6, A-2  
Accuracy, 4-12, B-8, B-9  
Addition: +, 2-4, A-2  
ALPHA, ALPHA-LOCK, 1-8  
Angle entry indicators (¡, ), 2-14,  
A-2, A-14  
ANGLE menu, 2-14, 2-15  
Angle MODE, 1-11  
B
r
b variable, 9-15 to 9-17, A-26  
Batteries, 1-2, 1-3, B-2 to B-7  
bºc MODE, 1-9, 1-11, 3-4, A-2  
8bºc, 3-9, A-2  
ANS, 6, 1-16, 8-2, 10-4  
APD, 1-2  
Applications  
BOX (VARS) menu, 1-19, 9-17  
BOX plot, 9-19 to 9-21  
Break, 1-7, 10-4, B-11  
Box with lid, 7 to 13  
Building height and city size,  
9-2 to 9-7  
Busy indicator, 1-5, B-10  
Compound interest, 5 , 6  
Generating a sequence, 8-2  
Graphing a circle, 4-2  
Graphing inequalities, 11-14  
Graphing the inverse of a function,  
11-10 to 11-11  
Graphing a piecewise function,  
11-12 to 11-13  
Graphing a polar equation,  
11-15  
C
c variable, 9-17, A-26  
Canceling a menu, 4, 1-18  
CHECK RAM screen, 12-2  
Circles, 4-2  
Guess the coefficients, 11-16  
Lottery chances, 2-2  
Newton’s numerical solve routine,  
11-4 to 11-5  
Numerical integration,  
11-6 to 11-7  
and spinners, 11-2  
Path of a ball, 5-2  
Rolling a die, 10-2 to 10-3  
Roots of a function, 6-2  
Shading a graph, 7-2  
Unit circle and trig curves, 11-3  
Windows variables store and recall,  
11-8 to 11-9  
list, 9-2, 9-11, 9-13, A-2  
menu, 4, 1-18  
CLRDRAW, 4-11, 7-3, 7-12, A-2  
CLRHOME, 10-2, 10-13, A-2  
CLRLIST, 9-2, 9-11, 9-13, A-2  
Coefficients (regression equation),  
9-15 to 9-17  
Combinations (probability), 2-13,  
A-10  
Commands, x, 10-4 to 10-6  
Compare, 2-16  
Concatenating commands, 1-6, 1-15  
CONNECTED MODE, 1-9, 1-11, 4-4,  
A-3  
Working with fractions, 3-2 to  
3-3  
Arcsine, arccosine, arctangent. See  
SIN-1, COS-1, TAN-1  
Argument, x  
Contrast setting, 3, 1-3  
Index I-1  
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C (Cont.)  
D (Cont.)  
Conversions  
decimals, 2-7, 2-8, 3-8, 3-10, 82,  
A-3  
fractions, 3-8, 3-10, A-6  
polar to rectangular, 2-14, 2-15, A-13  
rectangular to polar, 2-14, 2-15, A-15, Division: à, 2-4, A-4  
A-16  
Coordinates, 4-12  
Correlation coefficient r, 9-15 to 9-17  
COS, COS , 2-4, A-3, B-9  
DOMAIN error, B-11  
DOT MODE, 1-9, 1-11, 4-4, A-4  
DRAW menu, 7-3 to 7-11  
DRAWF, 7-3, 7-6, A-4  
–1  
Cosine, 2-4, A-3, B-9  
CTL (PRGM) menu, 10-7 to 10-10  
stat data, 9-18 to 9-21  
Cube:3, 2-7, 2-8, A-3  
Cube root: 3, 2-7, 2-8, A-3  
Cursor coordinates, 4-12, B-8  
Cursor keys, 1-8  
Cursors, 1-5, 1-8  
Curve fitting, 9-18 to 9-21  
E
H, 2-9  
D
DATA TYPE error, B-11  
8DEC, 2-7, 2-8, 3-8, 3-10, 8-2, A-3  
Decimal display, 1-10, 2-8, A-3  
Decimal window, 4-15, 4-17, A-19  
DEGREE MODE, 1-9, 1-11, 2-14, 4-4,  
A-3  
e (natural log), 2-5, A-8, B-9  
Editors, 1-8  
list, 9-9 to 9-12  
Degree notation ¡, 2-14, A-3  
Deleting  
characters, 1-8  
from memory, 12-3  
Element  
@TBL variable, 6-2, 6-3, 6-5, 6-6  
@X, @Y, 4-10, 4-17, A-26, B-8  
Dependent variable, 6-4 to 6-6  
Derivative. See Numerical derivative  
Difficulty, in case of, B-10  
DIM, 8-6, 8-7, A-3  
Dimension (list), 8-6, 8-7, A-3  
DIM MISMATCH error, B-11  
DISP, 10-3, 10-11, 10-13, A-3  
DISPGRAPH, 9-24, 10-11, 10-13,  
A-3  
list, 8-3 to 8-5  
END, 10-3, 10-7 to 10-9, A-4  
fractions, 3-6  
functions, 1-7, 4-5 to 4-7,  
5-3, 6-4, A-26  
lists, 8-3 to 8-5, 9-10 to 9-12  
negative numbers, 1-21, 2-6,  
A-11  
Display, 1-4, 1-5  
programs, 10-5 to 10-6  
statistics, 9-2 to 9-24  
EOS, 1-20, 1-21  
contrast, 3, 1-3, B-2, B-10  
cursors, 1-5, 1-8  
decimal, 2-8, A-3  
EQ (VARS) menu, 1-19, 9-17  
Equal: =, 2-16, A-4  
fraction, 3-8, 3-10, A-6  
I-2 Index  
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G
Getting Started. See Applications  
GOTO, 10-7, 10-10, A-6, B-12  
E (Cont.)  
Equation Operating System, 1-20,  
1-21  
Equations, parametric, 5-2 to 5-6  
Erasing a program, 10-4, 12-3  
Errors, 1-22, 8-5, 10-4, B-11 to B-13  
Evaluating expressions, 1-6, 3-4  
Evaluating functions, 4-7  
Executing programs, 10-5  
Exponent: E, 1-7, A-4  
accuracy, 4-12, B-8  
defining, 4-3, 5-3  
displaying, 12, 4-11, 5-5  
Greater than: >, 2-16, A-6  
Greater than or equal: , 2-16, A-6  
GRIDOFF, GRIDON, 4-11, 7-6, A-6  
Exponential regression, 9-14,  
9-16, A-5  
EXPREG, 9-14, 9-16, A-5  
Expressions, x, 1-6  
F
F (frequency), 9-19, 9-20  
Factorial:!, 2-12, 2-13, A-5, B-9  
Features, 14  
FIX MODE, 1-9, 1-10, A-5  
FLOAT MODE, 1-9, 1-10, A-5  
FNOFF, FNON, 4-8, A-5  
FOR(, 10-9, A-5  
H
HISTOGRAM, 9-19  
HORIZONTAL, 7-3, 7-5, A-7  
I
IF, 10-7, 10-8, A-7  
FPART, 2-10, A-6  
FRACTION menu, 3-8, 3-10  
Fractional part, 2-10, A-6  
Fractions  
Independent variable, 4-5, 6-3, 6-5,  
Input to programs, 10-11 to 10-13  
I/O menu, 10-11 to 10-13  
converting, 3-8 to 3-10  
entering, 3-6  
in expressions, 3-5  
mixed, 3-6  
modes, 3-4, 34-8, 3-5  
simple, 3-6  
simplifying, 3-8  
INT, 2-10, A-7  
8FRAC, 3-10, A-6  
Free-moving cursor, 4-12, 5-6  
Frequency, 9-19, 9-20  
FUNC MODE, 1-9, 1-11, 4-4, 7-3, A-6  
Functions, x, 1-6, 1-7, 2-3, B-9  
clearing, 4-6  
Integer part, 2-10, A-8  
Interrupt, 1-7, 10-4, B-11  
INVALID error, B-12  
INVALID DIM error, B-12  
Inverse: –1, 2-4, A-7  
log, 2-5  
editing, 4-6  
entering, 4-7  
trig, 2-4  
defining, 4-5, 4-6, 5-3  
evaluating, 4-7  
IPART, 2-10, A-8  
graphing, 4-2 to 4-18  
parametric, 5-2 to 5-6  
selecting, 4-8, 5-4  
Index I-3  
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K
L
M (Cont.)  
MAXX, MAXY, 9-17, 9-19, 9-21  
MEAN(, 8-9, A-9  
MED, 9-17, 9-19, 9-21, A-26  
keyboard, 2  
Ln (lists), 8-2 to 8-5, A-26  
LABEL error, B-12  
MEMORY menu, 12-2 to 12-4  
MEMORY screens, 12-2, 12-3, 12-4  
Menu map, A-20 to A-25  
Menus, x, 4, 1-17 to 1-19  
ANGLE, 2-14, 2-15  
Labels (program), 10-10  
Last Answer, 1-16, 10-4  
Last Entry, 1-14, 1-15, 10-4  
LBL, 10-7, 10-10, A-8, B-12  
Less than: <, 2-16, A-8  
Less than or equal: , 2-16, A-8  
LINE(, 7-3, 7-4, A-8  
Line (stat), 9-18, 9-20 to 9-21  
Linear regression, 9-15, 9-16, A-8  
LINREG, 9-14 to 9-16, A-8  
LIST MATH menu, 8-9, 8-10  
LIST OPS menu, 8-6 to 8-8  
Lists, x, 8-2 to 8-10  
BOX (VARS), 1-19, 9-17  
DRAW, 7-3 to 7-9  
EQ (VARS), 1-19, 9-17  
I/O (PRGM), 10-11 to 10-13  
LIST OPS, 8-6 to 8-8  
MATH MATH, 2-7 to 2-9  
MEMORY, 12-2 to 12-4  
NUM (MATH), 2-10, 2-11  
POINTS (DRAW), 7-10, 7-11  
PRB (MATH), 2-12, 2-13  
PRGM EXEC, 10-5, 10-10, 10-14  
PRGM EDIT, 10-6  
PRGM NEW, 10-5  
G (VARS), 1-19, 9-17  
STAT CALC, 9-14 to 9-17  
arguments, 2-3, 8-5  
copying, 8-3  
deleting, 9-11, 9-13  
dimension, 8-6, 8-7, A-3  
displaying, 8-4  
editing, 9-10, 9-11  
elements, 9-10 to 9-12  
entering, 8-3 to 8-5, 9-10 to 9-12  
in expressions, 8-3  
graphing, 8-4  
STAT MARK, 9-18, 9-20, 9-23  
STAT PLOTS, 9-18 to 9-20  
STAT TYPE, 9-18 to 9-21  
recalling values, 8-4  
saving, 8-3  
storing values, 8-4  
variables, 8-2 to 8-5, A-26  
viewing, 8-4  
X/Y (VARS), 1-19, 9-17  
LN, 2-5, A-8, B-9  
LNREG, 9-14, 9-16, A-9  
LOG, 2-5, A-9, B-9  
MIN(, 2-10, 2-11, 8-9, A-9, A-10  
Minimum, 2-10, 2-11, 8-9, 9-17, 9-17,  
9-19, 9-21  
Logarithm, 2-5, A-9  
Logarithmic regression, 9-16, A-9  
MINX, MINY, 9-17, 9-19, 9-21  
Modes, 1-9 to 1-11, 3-5, 4-4, 5-3  
MODE error, B-12  
M
MANSIMP MODE, 1-9, 1-11, 3-5, A-9  
MARK (STAT), 9-20 9-23  
MATH menu, 2-7 to 2-13  
MAX(, 2-10, 2-11, 8-9, A-9  
Maximum, 2-10, 2-11, 8-9, 9-17, 9-19,  
9-21  
Models, 9-15, 9-16  
Multi-argument functions, 1-20  
Multiple entries, 1-6, 1-15  
Multiplication: ×, 1-21, 2-4, A-10  
I-4 Index  
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N
n (statistics), 9-17, A-26  
Natural log, 2-5, A-8  
nCr, 2-12, 2-13, A-10  
NDERIV(, 2-7, 2-9, A-10  
PRGM EDIT menu, 10-6  
PRGM I/O menu, 10-11 to 10-13  
PRGM NEW menu, 10-2, 10-5  
Probability, 2-2, 2-12, 2-13, A-10,  
Product of a sequence, 8-10  
Program editor, 10-6, 10-7, 10-11  
Programs, 10-2 to 10-14  
commands, 10-5  
-
Negation: , 1-21, 2-6, A-11  
NEST LEVEL error, B-12  
NORMAL MODE, 1-9, 1-10, A-11  
Not equal: ƒ, 2-16, A-11  
nPr, 2-12, A-11  
NUM (MATH) menu, 2-10, 2-11  
Numerical derivative, 2-7, 2-9, A-10  
erasing, 10-4  
P8Rx(, P8Ry(, 2-14, 2-15, A-13  
PT-CHANGE(, PT-OFF(, PT-ON(, 7-10,  
7-11, A-13  
O
OFF, ON, 3, 1-2  
1-VAR STATS, 9-14, 9-15, A-11  
One-variable statistics, 9-14, 9-15,  
A-11  
OVERFLOW error, B-12  
Q1, Q3, 9-17, 9-19, 9-21, A-26  
QUADREG, 9-14, 9-16, A-14  
Quartiles, 9-17, 9-19  
P
Panning, 4-13, 5-6  
PARAM MODE, 1-9, 1-11, 4-4, 5-3,  
A-11  
Parametrics, 1-19, 5-2 to 5-6  
Parentheses, 1-21  
PAUSE, 10-7, 10-9, 10-13, A-12  
Pausing a program, 10-7, 10-9, 10-13,  
A-12  
Permutations, 2-12, 2-13, A-11  
Pi: p, 2-6, A-12  
ô (radian notation), 2-14, A-14  
r variable, A-26  
Pixel, x, 4-17, B-8  
RANDINT(, 2-12, 2-13, A-14  
Random numbers, 2-12, 2-13, A-14  
5-6, A-15, A-16  
Rectangular to polar, 2-14, 2-15,  
A-16, A-17  
PLOTn(, 9-18 to 9-24, A-12  
PLOTSOFF, PLOTSON, 9-21, A-12  
Plotting graphs, 4-11, 4-14  
Plotting stat data, 9-18 to 9-21,  
9-23 to 9-24  
POINTS (DRAW) menu, 7-10, 7-11,  
A-13  
Polar to rectangular, 2-14, 2-15,  
A-13  
Power of ten: 10^, 2-5, A-12, B-9  
Power regression, 9-14, 9-16, A-14  
Powers:^, 2-5, A-12  
PRB (MATH) menu, 2-12, 2-13  
PRGM_, 10-7, 10-10, 10-14, A-13  
PRGM CTL menu, 10-7 to 10-10  
REGEQ (regression equation),  
9-4 to 9-5, 9-15, A-26  
Regressions, 9-4, 9-5, 9-14 to 9-16  
Relational operators, 2-16  
REMANINDER(, 2-10, 2-11, A-14, A-15  
Reserved variables, A-26  
Resetting, 3, 12-4  
Index I-5  
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R (Cont.)  
Residuals, 9-6, 9-7  
RETURN, 10-7, 10-10, A-15  
root x, 2-7, 2-8, A-15, B-9  
ROUND(, 2-10, A-15  
S (Cont.)  
STAT EDIT menu, 9-9 to 9-13  
9-9 to 9-13  
STAT MARK menu, 9-20, 9-23  
STAT PLOT error, B-13  
STAT TYPE menu, 9-18 to 9-21  
Statistics, 1-19, 9-1 to 9-24  
9-14 to 9-17  
Running programs, 10-5  
R8Pr(, R8Pq(, 2-14, 2-15, A-15, A-16  
S
SCATTER plot, 9-18, 9-20  
SCI MODE, 1-7, 1-9, 1-10, A-16  
Scientific notation, 1-7, 1-9, 1-10,  
A-16  
calculations, 9-2 to 9-7,  
9-14 to 9-16  
in programs, 9-22  
2nd, 1-8  
Selecting from a menu, 4, 1-17  
Selecting functions, 1-19, 4-8, 5-4  
SEQ(, 8-2, 8-6, 8-8, 8-10, A-16  
Sequence  
STOP, 10-7, 10-10, A-18  
Stopping, 1-7, 10-4, 10-7, 10-10  
Storing, 1-13, 1-16, 8-3, 8-4  
Subroutines, 10-10, 10-14  
Summation, 8-10, A-18  
generating, 8-2, 8-6, 8-8, 8-10,  
A-16  
product, 8-10  
sum, 8-10  
SEQUENTIAL mode, 1-9, 1-11, 4-4,  
A-16  
Service information, B-14, B-15  
SHADE(,7-3, 7-9, A-16, A-17  
SHADE_Y>(, 7-2, 7-3, 7-7, A-17  
SHADE_Y<(, 7-2, 7-3, 7-8, A-17  
sX, sY, 9-17, A-26  
G (VARS) menu, 1-19, 9-17  
GX, GY, GX2, GY2, GXY, 9-16, 9-17,  
A-26  
T
úSIMP, 3-3, 3-8, A-17  
SIMUL, 1-9, 1-11, 4-4, A-17  
SIN, SIN , 2-4, A-17, B-9  
T variable, 5-3, 5-4, 6-3, A-26  
TABLE SETUP screen, 6-2, 6-3  
Table variables, 1-19, 6-3, 6-5  
–1  
Sine, 2-4, A-17, B-9  
Smart Graph, 4-11, 4-14, 5-5  
SORTA(, SORTD(, 8-6, 9-9, 9-13, A-17  
Sorting lists, 8-6, 9-3, 9-13  
Square: 2, 2-5, A-18  
TAN, TAN , 2-4, A-18, A-19, B-9  
TBLMIN, 1-19, 6-2, 6-3, 6-5  
TEST menu, 2-16  
Square root: , 2-5, A-18, B-9  
Square Window, 4-2, 4-15, 4-17,  
A-19  
Standard deviation, 9-17  
Standard Window, 4-2, 4-9, 4-15,  
4-17, A-19  
THEN, 10-7, 10-8, A-19  
q variable, 1-12, A-26  
TMAX, TMIN, 5-4, 5-5, B-13  
TRACE, 4-13, 4-14, A-19  
Trace, 12, 4-13, 4-14, 5-6, 9-21  
Trig functions, 2-3  
STAT error, B-13  
TSTEP, 5-4, 5-5, 5-6, B-8, B-13  
STAT CALC menu, 9-14 to 9-17  
I-6 Index  
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T (Cont.)  
Turning functions on and off, 1-19,  
4-8, 5-4  
Turning the TI-80 on and off, 3,  
1-2  
2-VAR STATS, 9-14, 9-15, A-19  
Two-variable statistics, 9-14, 9-15,  
A-19  
Y (Cont.)  
Yn, 1-19, 4-5 to 4-7, 10-12, A-26  
Y1, Y2, Y3, 9-14, 9-15, A-26  
YnT functions, 1-19, 5-3, A-26  
Y= editor, 1-19, 4-5 to 4-7, 5-3, 6-4,  
A-26  
Y= functions. See Yn, XnT, functions  
YFACT variable, 4-16, 4-18  
YL (Y-list), 9-15, 9-18, 9-20  
YMAX, YMIN, YSCL, 4-9, 4-10, 4-12,  
4-13, 4-17, 5-2, 5-4, 9-19,  
U
UNDEFINED error, B-13  
A-26, B-8, B-12, B-13  
V
Variables, x, 1-12, 1-13, A-26  
VARS menu, 1-19  
VERTICAL, 7-3, 7-5, A-19  
Vertical line, 7-5  
Z
ZDECIMAL, 4-15, 4-17, A-19  
ZOOM, 13, 1-18, 4-15 to 4-18,  
5-6  
Viewing rectangle, viewing window. See  
Window  
ZOOM error, B-13  
ZOOM FACTORS, 4-18  
ZOOM IN, 4-15, 4-16  
ZOOM menu, 4-15 to 4-17  
ZSTANDARD, 4-15, 4-17, 5-6, A-19  
W
Warranty information, B-14, B-16  
Window, 11, 1-19, 4-9 to 4-10,  
4-15 to 4-18, 5-3 to 5-6,  
9-21, A-26, B-8  
WINDOW RANGE error, B-13  
@TBL, 6-2, 6-3, 6-5, 4-18, 4-19, 6-6  
@X, @Y, 4-10, 4-17, A-26, B-8  
X
X,T key, 1-8, 4-5, 5-3  
v, 9-17, A-26  
sX, sY, 9-17, A-26  
G (VARS) menu, 1-19, 9-17  
GX, GY, GX2, GY2, GXY, 9-17, A-26  
q, 1-12, A-26  
X, 4-5, 4-11 to 4-13, 6-3, A-26, B-11  
XnT functions, 1-19, 5-3, A-26  
XFACT variable, 4-16  
XL (X-list), 9-15, 9-18, 9-20  
XMAX, XMIN, XSCL, 4-9, 4-13, 4-9,  
4-10, 4-12, 4-17, 5-2, 5-4,  
9-19, A-26, B-8, B-12, B-13  
X/Y (VARS) menu, 1-19, 9-17  
XYLINE, 9-18, 9-20, 9-21  
Y
w, 9-17, A-26  
Y, 4-11 to 4-13, A-26, B-11  
Index I-7  
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TI-80  
STAT PLOT  
X,T  
FRAC  
x
{
}
b
c
x
x
x
E
Download from Www.Somanuals.com. All Manuals Search And Download.  
Download from Www.Somanuals.com. All Manuals Search And Download.  

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