Texas Instruments TI-81 - Using the Y-VARS Menu; Using the Name of a Function in the Y= List as a Variable

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Table of Contents5
Using this Manual Effectively9
The Keyboard12
Entering a Calculation14
Continuing a Calculation15
Graphic Features16
Graphic Keys16
Defining Functions to Graph17
Checking the Viewing Rectangle18
Displaying the Graph19
Zooming in on the Graph20
Moving between the Graph and Range Screens21
Moving the Cursor Along a Function22
Using Zoom Box24
Other Capabilities26
Operation27
The Keyboard Overview28
The Second and Alpha Keys29
Turning on and off30
Setting the Display Contrast31
When to Replace Batteries31
The Display32
The Home Screen32
Display Cursors32
Menu Screens33
Graph Screens33
Editing Screens33
The Equation Operating System34
Order of Evaluation34
Implied Multiplication35
Using Parentheses35
Entering a Negative Number35
Negation35
Entering Expressions for Evaluation36
Editing Expressions38
The Cursor-Movement Keys38
The Edit Keys38
Inserting in Expressions39
Deleting from Expressions39
Setting Modes40
Checking Mode Settings40
Changing Mode Settings40
Leaving the Mode Screen40
Normal, Scientific, or Engineering Notation Display Format41
Floating or Fixed Decimal Display Setting41
Radians or Degrees Angle Setting41
Function or Parametric Graphing Setting42
Connected Line or Dot Graph Display42
Sequential or Simultaneous Plotting42
Grid off or Grid on42
Entering Numbers in Scientific Notation43
Selecting from a Menu44
The Menu Keys44
Leaving a Menu44
Moving from One Menu to Another45
Selecting an Item from a Menu45
Using a Menu Item in an Expression45
Storing and Recalling Variable Values46
Valuables46
Storing Valuables in Variables46
Displaying the Value of a Variable47
Using Variables in Expressions47
Storing and Recalling a Value from a Variable47
Last Answer48
Using Last Answer in Place of Parentheses48
Last Entry49
Performing Iterative Calculations with Last Entry49
Clearing Expressions and Entries50
Clearing a Value50
Clearing the Home Screen50
Using CLEAR to Cancel a Menu50
Leaving a Menu or Edit Screen51
Error Conditions52
Diagnosing Errors52
Correcting an Error53
Resetting54
Results of Resetting54
Math and Test Operations55
The Keyboard Math Functions56
Using the MATH Menus57
Using the MATH (Mathematical) Menu58
Using the NUM (Number) Menu60
Using the HYP (Hyperbolic) Menu61
Using the PRB (Probability) Menu62
Using the TEST (Relational) Menu63
Using the Relational Operations64
Notes about TEST Menu Operations64
Function Graphing65
Defining a Graph66
Setting Graph Modes67
Checking Graph Modes67
Changing Graph Modes67
Defining Functions in the Y= List68
Selecting Functions70
Turning a Function "On" or "Off"70
Defining the Viewing Rectangle71
Displaying a Graph72
The GRAPH Screen72
The "Smart Graph" Feature72
Exploring a Graph with the Free-Moving Cursor73
Exploring a Graph with the TRACE Feature74
Exploring a Graph with the ZOOM Features75
The ZOOM Menu75
Defining the Zoom Box76
Using Zoom in77
Using Zoom out78
Setting Zoom Factors79
Checking Xfact and Yfact79
Changing Xfact and Yfact79
Leaving Zoom Factors79
Using Other Zoom Features80
Square80
Standard80
Trig/Integer80
Using RANGE Variables81
Storing a Range Variable81
Using the Y-VARS Menu82
Using the Name of a Function in the Y= List as a Variable82
Turning a Function in the Y= List on or off83
Graphing a Circle84
Parametric Graphing85
Defining and Displaying a Parametric Graph86
Displaying the Components of Parametric Equations86
Entering Expressions to Define Components of Parametric Equations86
Selecting Parametric Equations87
Setting the RANGE Variables87
Using the RANGE Variables and Y-VARS Menus88
Exploring a Parametric Graph89
The Trace Feature89
The Zoom Features89
Simulating Motion90
Graphing a Polar Equation91
Graphing a Parametric Equation92
The DRAW Features93
The DRAW Menu94
The DRAW Instructions95
Before Drawing on a Graph95
Leaving DRAW95
Clearing Drawing on a Graph96
Drawing a Line97
Using the Line Instruction from a Graph97
Using the Line Instruction from the Home Screen or a Program97
Drawing a Point98
Using the PT-On Instruction from a Graph98
Using the PT-On Instruction from the Home Screen or a Program98
Using the PT-Off and PT-Chg Instructions98
Drawing a Function99
Using the Drawf Instruction99
Shading an Area on a Graph100
The Shading Parameters100
Shading a Drawing101
Shading an Area between Two Functions102
Using Matrices103
The MATRX (Matrix) Menus104
Defining a Matrix105
Selecting a Matrix105
Accepting or Changing Matrix Dimensions105
Entering and Editing Matrix Elements106
Leaving the MATRIX Edit Screen106
Clearing a Matrix106
Displaying a Stored Matrix107
Copying One Matrix to Another107
Using a Matrix in an Expression107
Results of Matrix Calculations107
Matrix Math Functions108
Using the Row Operations110
The Rowswap Function110
Swapping Rows in a Matrix110
Using the Row+ Function111
Using the *Row Function111
Using the *Row+ Function111
Storing and Recalling a Matrix Element112
Using a Matrix Element in an Expression112
Storing and Recalling a Matrix Dimension113
Reducing a Matrix114
Performing Statistical Calculations115
The STAT (Statistical) Menus116
Setting up a Statistical Analysis117
Statistical Data117
Clearing Previous Data117
Entering and Editing Data118
Entering a New Set of Data118
Leaving the DATA Edit Screen118
Editing Statistical Data119
Inserting Statistical Data119
Deleting Statistical Data119
Sorting Statistical Data120
Reviewing Sorted Data120
Calculating One-Variable Statistics121
Calculating Two-Variable Statistics122
The Regression Models123
Statistical Results Variables124
The VARS Menu124
Displaying a Statistical Results Variable126
Using a Statistical Results Variable in an Expression126
Using Regeq127
Drawing Statistical Data128
Plotting the Data128
Histogram129
Scatter Plot129
Line Drawing129
Storing and Recalling a Data Value130
Analyzing One-Variable Statistics131
Analyzing Two-Variable Statistics132
Programming133
The PRGM (Program) Menus134
While Entering or Editing a Program135
While a Program Is Executing135
Entering a Program136
Selecting a Program136
Notes about Entering Program Commands137
Leaving the Program Edit Screen137
Editing a Program Command138
Inserting a Program Command138
Deleting a Program Command138
Executing a Program from the Home Screen139
"Breaking" a Program139
Erasing a Program140
Accessing the Programming Instructions Menus141
The Control Instructions142
The Lbl and Goto Instructions142
The if Instructions142
The IS Instruction143
The DS Instruction143
The Pause Instruction143
The End Instruction143
The Input/Output Instructions144
The Disp Instruction144
The Input Instruction145
The Disphome Instruction145
The Dispgraph Instruction145
The Clrhome Instruction145
Sample Program146
Program Features147
Calling Other Programs (the Execute Instructions)148
Calling a Program from Another Program148
Notes about Calling Programs149
Setting Modes from a Program150
The MODE Menu150
Applications151
Solving a System of Linear Equations152
Solving a System of Nonlinear Equations153
Graphing a Piecewise Defined Function154
Exploring End Behavior of a Rational Function155
Analyzing Statistical Data Graphically156
Determining Maximum Volume of an Open Box157
Simulating Motion with Parametric Equations158
Graphing the Inverse of a Relation160
Graphing the Unit Circle and Trigonometric Curves161
Program: Numerical Solve Routine162
Program: Numerical Integration164
Program: Building a Table of Function Values166
Program: Plotting the Derivative168
Program: Guess the Coefficients170
Commands171
Replacing the Batteries182
Computational Accuracy183
Error Codes184
Handling a Difficulty187
Support and Service Information188
Product Support188
Other TI Products and Services188
Product Service188
Warranty Information189
Customers in the U.S. and Canada Only189
All Customers Outside the U.S. and Canada189
Index190

Texas Instruments TI-81 - Using the Y-VARS Menu; Using the Name of a Function in the Y= List as a Variable

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