Texas Instruments TI-89 user guide: Menus

Menus

To leave the keyboard uncluttered, the TI-89 / TI-92 Plus uses menus to access many operations. This section gives an overview of how to select an item from any menu. Specific menus are described in the appropriate chapters of this guidebook.

Displaying a Menu

Selecting an Item from a Menu

To select an item from the displayed menu, either:

• Press the number or letter shown to the left of that item. For a letter on the TI-89, press [alpha] and then a letter key. — or —
• Use the cursor pad ◀ and ▶ to highlight the item, and then press [ENTER]. (Note that pressing ▶ from the first item moves the highlight to the last item, and vice versa.)

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Items Ending with ▶ (Submenus)

If you select a menu item ending with ▶, a submenu is displayed. You then select an item from the submenu.

Note: Because of limited screen size, the TI-89 overlaps these menus as:

For example, List displays a submenu that lets you select a specific List function.

↓ indicates that you can use the cursor pad to scroll down for additional items.

For items that have a submenu, you can use the cursor pad as described below.

• To display the submenu for the highlighted item, press \textcircledD. (This is the same as selecting that item.)
• To cancel the submenu without making a selection, press \textcircledC. (This is the same as pressing ESC.)
• To wrap to the last menu item directly from the first menu item, press \textcircledS. To wrap to the first menu item directly from the last menu item, press \textcircledS.

Items Containing “…” (Dialog Boxes)

If you select a menu item containing “…” (ellipsis marks), a dialog box is displayed for you to enter additional information.

For example, Save Copy As ... displays a dialog box that prompts you to select a folder name and type a variable name.

\rightarrow indicates that you can press \textcircledD to display and select from a menu.

An input box indicates that you must type a value. (Alpha-lock is automatically turned on for the TI-89. See page 22.)

After typing in an input box such as Variable, you must press ENTER twice to save the information and close the dialog box.

Canceling a Menu

To cancel the current menu without making a selection, press ESC. Depending on whether any submenus are displayed, you may need to press ESC several times to cancel all displayed menus.

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To move from one toolbar menu to another without making a selection, either:

• Press the key (F1, F2, etc.) for the other toolbar menu. — or —

• Use the cursor pad to move to the next (press \blacktriangleright) or previous (press \blacktriangleleft) toolbar menu. Pressing \blacktriangleright from the last menu moves to the first menu, and vice versa.

When using \blacktriangleright, be sure that an item with a submenu is not highlighted. If so, \blacktriangleright displays that item’s submenu instead of moving to the next toolbar menu.

Example: Selecting a Menu Item

Round the value of \pi to three decimal places. Starting from a clear entry line on the Home screen:

1. Press 2nd [MATH] to display the MATH menu.

2. Press 1 to display the Number submenu. (Or press ENTER since the first item is automatically highlighted.)

3. Press 3 to select round. (Or press \blacktriangleright \blacktriangleright and ENTER.)

4. Press 2nd [\pi] , 3 ] and then ENTER to evaluate the expression.

Selecting the function in Step 3 automatically typed round( on the entry line.

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Using the Custom Menu

The TI-89 / TI-92 Plus has a custom menu that you can turn on and off at any time. You can use the default custom menu or create your own as described in Chapter 17: Programming.

Turning the Custom Menu On and Off

When you turn on the custom menu, it replaces the normal toolbar menu. When you turn it off, the normal menu returns. For example, from the Home screen’s normal toolbar menu, press [2nd] [CUSTOM] to toggle the custom menu on and off.

Note: You can also turn the custom menu on and off by entering CustmOn or CustmOff in the entry line and pressing [ENTER].

Home screen normal toolbar menu

Custom menu

Unless the menu has been modified, the default custom menu appears.

Tip: A custom menu can give you quick access to commonly used items. Chapter 17 shows you how to create custom menus for the items you use most often.

Restoring the Default Custom Menu

If a custom menu other than the default is displayed and you want to restore the default:

1. From the Home screen, use [2nd] [CUSTOM] to turn off the custom menu and display the Home screen’s normal toolbar menu.
2. Display the Clean Up toolbar menu, and select 3:Restore custom default. TI-89: [2nd] [F6] TI-92 Plus: [F6] This pastes the commands used to create the default menu into the entry line.
3. Press [ENTER] to execute the commands and restore the default.

Note: The previous custom menu is erased. If that menu was created with a program (Chapter 17), it can be recreated later by running the program again.

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Selecting an Application

The TI-89 / TI-92 Plus has different applications that let you solve and explore a variety of problems. You can select an application from a menu, or you can access commonly used applications directly from the keyboard.

From the APPLICATIONS Menu

Note: To cancel the menu without making a selection, press [ESC].

1. Press [APPS] to display a menu that lists the applications.
2. Select an application. Either:
   • Use the cursor pad ◀ or ▶ to highlight the application and then press [ENTER]. — or —
   • Press the number or letter for that application.

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From the Keyboard

You can access commonly used applications from the keyboard. On the TI-89 for example, ◆ [Y=] is the same as pressing ◆ and then [F1]. This guidebook uses the notation ◆ [Y=], similar to the notation used in second functions.

On the TI-92 Plus, applications are listed above the QWERTY keys.

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Setting Modes

Modes control how numbers and graphs are displayed and interpreted. Mode settings are retained by the Constant Memory™ feature when the TI-89 / TI-92 Plus is turned off. All numbers, including elements of matrices and lists, are displayed according to the current mode settings.

Checking Mode Settings

Press [MODE] to display the MODE dialog box, which lists the modes and their current settings.

Indicates you can scroll down to see additional modes.

There are three pages of mode listings. Press [F1], [F2], or [F3] to quickly display a particular page.

\rightarrow indicates that you can press \blacktriangleright or \blacktriangleleft to display and select from a menu.

Note: Modes that are not currently valid are dimmed. For example, on Page 2, Split 2 App is not valid when Split Screen = FULL. When you scroll through the list, the cursor skips dimmed settings.

Changing Mode Settings

From the MODE dialog box:

1. Highlight the mode setting you want to change. Use \blacktriangleright or \blacktriangleleft (with [F1], [F2], or [F3]) to scroll through the list.
2. Press \blacktriangleright or \blacktriangleleft to display a menu that lists the valid settings. The current setting is highlighted.
3. Select the applicable setting. Either:
   • Use \blacktriangleright or \blacktriangleleft to highlight the setting and press [ENTER]. — or —
   • Press the number or letter for that setting.
4. Change other mode settings, if necessary.
5. When you finish all your changes, press [ENTER] to save the changes and exit the dialog box.

Tip: To cancel a menu and return to the MODE dialog box without making a selection, press [ESC].

Important: If you press [ESC] instead of [ENTER] to exit the MODE dialog box, any mode changes you made will be canceled.

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Overview of the Modes

Note: For detailed information about a particular mode, look in the applicable section of this guidebook.

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Modes (continued)

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Using the Clean Up Menu to Start a New Problem

On the Home screen, the Clean Up toolbar menu lets you start a new calculation from a cleared state without resetting the TI-89 / TI-92 Plus’s memory.

Clean Up Toolbar Menu

From the Home screen, display the Clean Up menu by pressing:

TI-89: [2nd] [F6]
TI-92 Plus: [F6]

Tip: When defining a variable that you want to retain, use more than one character in the name. This prevents it from being deleted inadvertently by 1:Clear a–z.

Note: For information about checking and resetting memory or other system defaults, refer to Chapter 21.

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Using the Catalog Dialog Box

The CATALOG provides a way to access any built-in TI-89 / TI-92 Plus command (functions and instructions) from one convenient list. In addition, the CATALOG dialog box lets you select functions used in Flash applications or user-defined functions (if any have been loaded or defined).

Displaying the CATALOG

To display the CATALOG dialog box, press:

TI-89: [CATALOG]

TI-92 Plus: [2nd] [CATALOG]

The CATALOG defaults to F2 Built-in, which displays an alphabetic list of all pre-installed TI-89 / TI-92 Plus commands (functions and instructions).

Note: Options that are not currently valid are dimmed. For example, F1 Help is reserved for a future online help Flash application. F3 Flash Apps is dimmed if you have not installed a Flash application. F4 User-Defined is dimmed if you have not created a function or a program.

Selecting a Built-in Command from the CATALOG

When you select a command, its name is inserted in the entry line at the cursor location. Therefore, you should position the cursor as necessary before selecting the command.

1. Press: TI-89: [CATALOG] TI-92 Plus: [2nd] [CATALOG]

2. Press F2 Built-in.

Note: The first time you display the Built-in list, it starts at the top of the list. The next time you display the list, it starts at the same place you left it.

• Commands are listed in alphabetical order. Commands that do not start with a letter (+, %, \sqrt, \Sigma, etc.) are at the end of the list.
• To exit the CATALOG without selecting a command, press [ESC].

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3. Move the ► indicator to the command, and press [ENTER].

To move the ► indicator: One command at a time One page at a time To the first command that begins with a specified letter

Press or type: ⊙ or ⊕ [2nd] ⊙ or [2nd] ⊕ The letter key. (On the TI-89, do not press [alpha] first. If you do, you need to press [alpha] or [2nd] [a-lock] again before you can type a letter.)

Tip: From the top of the list, press ⊖ to move to the bottom. From the bottom, press ⊕ to move to the top.

I nformation about Parameters

For the command indicated by ►, the status line shows the required and optional parameters, if any, and their type.

Note: For details about the parameters, refer to that command's description in Appendix A.

From the example above, the syntax for factor is:

factor(expression) required — or — factor(expression,variable) optional

S electing a Flash Application Function

A Flash application may contain one or more functions. When you select a function, its name is inserted in the entry line at the cursor location. Therefore, you should position the cursor as necessary before selecting the function.

1. Press: TI-89: [CATALOG] TI-92 Plus: [2nd] [CATALOG]

2. Press [F3] Flash Apps. (This option is dimmed if no Flash applications are installed in the TI-89 / TI-92 Plus.)

• The list is alphabetized by function name. The left column lists functions. The right column lists the Flash application that contains the function. • Information about a function is displayed in the status line. • To exit without selecting a function, press [ESC].

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3. Move the ▶ indicator to the function, and press [ENTER].

Selecting a User-Defined Function or Program

You can create your own functions or programs and then use [F4] User-Defined to access them. For instructions on how to create functions, see “Creating and Evaluating User-Defined Functions” in Chapter 5, and “Overview of Entering a Function” in Chapter 17. See Chapter 17 for instructions on how to create and run a program.

When you select a function or program, its name is inserted in the entry line at the cursor location. Therefore, you should position the cursor as necessary before selecting the function or program.

1. Press:

   • TI-89: [CATALOG]
   • TI-92 Plus: [2nd] [CATALOG]

2. Press [F4] User-Defined. (This option is dimmed if you have not defined a function or created a program.)

• The list is alphabetized by function / program name. The left column lists functions and programs. The right column lists the folder that contains the function or program.
• If the function or program’s first line is a comment, the comment text is displayed in the status line.
• To exit without selecting a function or program, press [ESC].

3. Move the ▶ indicator to the function or program, and press [ENTER].

Note: Use the VAR-LINK screen to manage variables, folders, and Flash applications. See Chapter 21.

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Storing and Recalling Variable Values

When you store a value, you store it as a named variable. You can then use the name instead of the value in expressions. When the TI-89 / TI-92 Plus encounters the name in an expression, it substitutes the variable’s stored value.

Rules for Variable Names

A variable name:

• Can use 1 to 8 characters consisting of letters and digits. This includes Greek letters (but not π), accented letters, and international letters. Do not include spaces.
  • The first character cannot be a digit.
• Can use uppercase or lowercase letters. The names AB22, Ab22, aB22, and ab22 all refer to the same variable.
• Cannot be the same as a name that is preassigned by the TI-89 / TI-92 Plus. Preassigned names include:
  • Built-in functions (such as abs) and instructions (such as LineVert). Refer to Appendix A.
  • System variables (such as xmin and xmax, which are used to store graph-related values). Refer to Appendix B for a list.

Examples

Data Types

You can save any TI-89 / TI-92 Plus data type as a variable. For a list of data types, refer to getType() in Appendix A. Some examples are:

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Storing a Value in a Variable

Note: TI-89 users should use \boxedalpha as necessary when typing variable names.

1. Enter the value you want to store, which can be an expression.
2. Press \boxedSTO\triangleright. The store symbol (\triangleright) is displayed.
3. Type the variable name.
4. Press \boxedENTER.

To store to a variable temporarily, you can use the “with” operator. Refer to “Substituting Values and Setting Constraints” in Chapter 3.

Displaying a Variable

Note: Refer to Chapter 3 for information about symbolic manipulation.

1. Type the variable name.
2. Press \boxedENTER.

If the variable is undefined, the variable name is shown in the result.

In this example, the variable a is undefined. Therefore, it is used as a symbolic variable.

Using a Variable in an Expression

Tip: To view a list of existing variable names, use \boxed2nd \boxedVAR-LINK as described in Chapter 21.

1. Type the variable name into the expression.
2. Press \boxedENTER to evaluate the expression.

The variable’s value did not change.

If you want the result to replace the variable’s previous value, you must store the result.

Recalling a Variable’s Value

In some cases, you may want to use a variable’s actual value in an expression instead of the variable name.

1. Press \boxed2nd \boxedRCL to display a dialog box.
2. Type the variable name.
3. Press \boxedENTER twice.

In this example, the value stored in num1 will be inserted at the cursor position in the entry line.

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Reusing a Previous Entry or the Last Answer

You can reuse a previous entry by reexecuting the entry “as is” or by editing the entry and then reexecuting it. You can also reuse the last calculated answer by inserting it into a new expression.

Reusing the Expression on the Entry Line

When you press ENTER to evaluate an expression, the TI-89 / TI-92 Plus leaves that expression on the entry line and highlights it. You can type over the entry, or you can reuse it as necessary.

For example, using a variable, find the square of 1, 2, 3, etc.

As shown below, set the initial variable value and then enter the variable expression. Next, reenter to increment the variable and calculate the square.

Tip: Reexecuting an entry "as is" is useful for iterative calculations that involve variables.

\begin{tabular}{|l|l|l|} \hline On the TI-89: & On the TI-92 Plus: & Display \ \hline 0 [STO] & 0 [STO] & \blacksquare 0 \rightarrow num \ [2nd] [a-lock] NUM & NUM & 0 \rightarrow num \ ENTER & ENTER & MAIN F6 AUTO FUNC 1/30 \ \hline NUM [alpha] [+] 1 [STO] & NUM [+] 1 [STO] & \blacksquare 0 \rightarrow num \ [2nd] [a-lock] NUM & NUM & \blacksquare num + 1 \rightarrow num : num^2 \ [2nd] [:] NUM [^] 2 & [2nd] [:] NUM [^] 2 & num+1\rightarrownum:num^2 \ ENTER & ENTER & MAIN F6 AUTO FUNC 2/30 \ \hline ENTER ENTER & ENTER ENTER & \blacksquare 0 \rightarrow num \ & & \blacksquare num + 1 \rightarrow num : num^2 \ & & \blacksquare num + 1 \rightarrow num : num^2 \ & & \blacksquare num + 1 \rightarrow num : num^2 \ & & num+1\rightarrownum:num^2 \ & & MAIN F6 AUTO FUNC 4/30 \ \hline \end{tabular}

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Tip: Editing an entry lets you make minor changes without retyping the entire entry.

Using the equation A=πr², use trial and error to find the radius of a circle that covers 200 square centimeters.

The example below uses 8 as the first guess and then displays the answer in its approximate floating-point form. You can edit and reexecute using 7.95 and continue until the answer is as accurate as you want.

Note: When the entry contains a decimal point, the result is automatically displayed in floating-point.

Recalling a Previous Entry

You can recall any previous entry that is stored in the history area, even if the entry has scrolled off the top of the screen. The recalled entry replaces whatever is currently shown on the entry line. You can then reexecute or edit the recalled entry.

Note: You can also use the entry function to recall any previous entry. Refer to entry() in Appendix A.

For example:

If the entry line contains the last entry, [2nd] [ENTRY] recalls this entry.

If the entry line is edited or cleared, [2nd] [ENTRY] recalls this entry.

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Recalling the Last Answer

Each time you evaluate an expression, the TI-89 / TI-92 Plus stores the answer to the variable ans(1). To insert this variable in the entry line, press 2nd [ANS].

For example, 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. Find the area. 1.7 × 4.2 ENTER

2. Find the yield. 147 \div 2nd [ANS] ENTER

Variable ans(1) is inserted, and its value is used in the calculation.

Note: Refer to ans() in Appendix A.

Just as ans(1) always contains the last answer, ans(2), ans(3), etc., also contain previous answers. For example, ans(2) contains the next-to-last answer.

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Auto-Pasting an Entry or Answer from the History Area

You can select any entry or answer from the history area and “auto-paste” a duplicate of it on the entry line. This lets you insert a previous entry or answer into a new expression without having to retype the previous information.

Why Use Auto-Paste

The effect of using auto-paste is similar to [2nd] [ENTRY] and [2nd] [ANS] as described in the previous section, but there are differences.

Note: You can also paste information by using the F1 toolbar menu. Refer to "Cutting, Copying, and Pasting Information" in Chapter 5.

\begin{tabular}{lll} For entries: & Pasting lets you: & [2nd] [ENTRY] lets you: \ & Insert any previous & Replace the contents of the \ & entry into the entry & entry line with any previous \ & line. & entry. \ For answers: & Pasting lets you: & [2nd] [ANS] lets you: \ & Insert the displayed & Insert the variable ans(1), \ & value of any & which contains the last \ & previous answer & answer only. Each time you \ & into the entry line. & enter a calculation, ans(1) is \ & & updated to the latest answer. \ \end{tabular}

Auto-Pasting an Entry or Answer

1. On the entry line, place the cursor where you want to insert the entry or answer.
2. Press \ominus to move the cursor up into the history area. This highlights the last answer.
3. Use \ominus and \oplus to highlight the entry or answer to auto-paste.
   • \ominus moves from answer to entry up through the history area.
   • You can use \ominus to highlight items that have scrolled off the screen.

Tip: To cancel auto-paste and return to the entry line, press ESC.

Tip: To view an entry or answer too long for one line (indicated by \blacktriangleright at the end of the line), use \circledR and \circledL or [2nd] \circledR and [2nd] \circledL.

4. Press [ENTER]. The highlighted item is inserted in the entry line.

This pastes the entire entry or answer. If you need only a part of the entry or answer, edit the entry line to delete the unwanted parts.

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Status Line Indicators in the Display

The status line is displayed at the bottom of all application screens. It shows information about the current state of the TI-89 / TI-92 Plus, including several important mode settings.

Status Line Indicators

Note: To cancel [2nd], ◆, [alpha], or [↑], press the same key again or press a different modifier key.

Note: If the next key you press does not have a diamond feature or an associated letter, the key performs its normal operation.

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Status Line (continued)

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Finding the Software Version and ID Number

In some situations, you may need to find out information about your TI-89 / TI-92 Plus, particularly the software version and the unit's ID number.

Displaying the "About" Screen

From the Home screen, press F1 and then select A:About.

Your screen will be different than the one shown to the right.

Press ENTER or ESC to close the screen.

When Do You Need this Information?

The information on the About screen is intended for situations such as:

• If you obtain new or upgraded software for your TI-89 / TI-92 Plus, you may need to provide your current software version and/or the ID number of your unit.
• If you have difficulties with your TI-89 / TI-92 Plus and need to contact technical support, knowing the software version may make it easier to diagnose the problem.

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Symbolic Manipulation

3

• Preview of Symbolic Manipulation ........ 58
• Using Undefined or Defined Variables ........ 59
• Using Exact, Approximate, and Auto Modes ........ 61
• Automatic Simplification ........ 64
• Delayed Simplification for Certain Built-In Functions ........ 66
• Substituting Values and Setting Constraints ........ 67
• Overview of the Algebra Menu ........ 70
• Common Algebraic Operations ........ 72
• Overview of the Calc Menu ........ 75
• Common Calculus Operations ........ 76
• User-Defined Functions and Symbolic Manipulation ........ 77
• If You Get an Out-of-Memory Error ........ 79
• Special Constants Used in Symbolic Manipulation ........ 80

This chapter is an overview of the fundamentals of using symbolic manipulation to perform algebraic or calculus operations.

You can easily perform symbolic calculations from the Home screen.

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Preview of Symbolic Manipulation

Solve the system of equations 2x - 3y = 4 and -x + 7y = -12. Solve the first equation so that x is expressed in terms of y. Substitute the expression for x into the second equation, and solve for the value of y. Then substitute the y value back into the first equation to solve for the value of x.

This example is a demonstration of symbolic manipulation. A one-step function is available for solving systems of equations. (See page 73.)

58 Chapter 3: Symbolic Manipulation