[Scope: Advanced Graphing, Function, Parametric, Polar, Sequence, Solve. See dedicated app chapters for information about the other apps.]
Symbolic view functionality that is common to many apps is described in detail in this section. Functionality that is available only in a particular app is described in the chapter dedicated to that app.
Symbolic view is typically used to define a function or open sentence that you want to explore (by plotting and/or evaluating). In this section, the term definition will be used to cover both functions and open sentences.
Press Y to open Symbolic view.
Add a definition
With the exception of the Parametric app, there are 10 fields for entering definitions. In the Parametric app there are 20 fields, two for each paired definition.
1. Highlight an empty field you want to use, either by tapping on it or scrolling to it.
2. Enter your definition.
If you need help, see “Definitional building blocks” on page 72.
3. Tap or press E when you have finished.
Your new definition is added to the list of definitions.
Note that variables used in definitions must be in uppercase.
A variable entered in lowercase will cause an error message to appear.
Modify a definition
1. Highlight the definition you want to modify, either by tapping on it or scrolling to it.
2. Tap .
The definition is copied to the entry line.
3. Modify the definition.
4. Tap or press E when you have finished.
Definitional building blocks
The components that make up a symbolic definition can come from a number of sources.
• From the keyboard
You can enter components directly from the keyboard. To enter 2X2 – 3, just press 2AXjw3.
• From user variables
If, for example, you have created a variable called COST, you could incorporate that into a definition either by typing it or choosing it from the User menu (one of the sub-menus of the Variables menu). Thus you could have a definition that reads F1(X)=X2+COST.
To select a user variable, press a, tap , select User Variables, and then select the variable of interest.
• From Home variables
Some Home variables can be incorporated into a symbolic definition. To access a Home variable, press a, tap
, select a category of variable, and select the variable of interest. Thus you could have a definition that reads F1(X)=X2+Q. (Q is on the Real sub-menu of the Home menu.)
• From app variables
All settings, definitions, and results, for all apps, are stored as variables. Many of these variables can be incorporated into a symbolic definition. To access app variables, press a, tap , select the app, select the category of variable, and then select the variable of interest. You could, for instance, have a definition that reads
F2(X)=X2+X–Root. The value of the last root calculated in the Function app is substituted for Root when this definition is evaluated.
• From math functions
Some of the functions on the Math menu can be
incorporated into a definition. The Math menu is one of the Toolbox menus (D). The following definition combines a math function (Size) with a Home variable (L1):
F4(X)=X2–SIZE(L1). It is equivalent to x2–n where n is the number of elements in the list named L1. (Size is an option on the List menu, which is a sub-menu of the Math menu.)
• From CAS functions
Some of the functions on the CAS menu can be incorporated into a definition. The CAS menu is one of the Toolbox menus (D). The following definition incorporates the CAS function irem: F5(X)=X2+CAS.irem(45,7). (irem is entered by choosing Remainder, an option on the Division menu, which is a sub-menu of the Integer menu.
Note that any CAS command or function selected to operate outside the CAS is given the CAS. prefix.)
• From app functions
Some of the functions on the App menu can be
incorporated into a definition. The App menu is one of the Toolbox menus (D). The following definition incorporates the app function PredY:
F9(X)=X2+Statistics_2Var.PredY(6).
• From the Catlg menu
Some of the functions on the Catlg menu can be
incorporated into a definition. The Catlg menu is one of the Toolbox menus (D). The following definition incorporates
a command from that menu and an app variable:
F6(X)=X2+INT(Root). The integer value of the last root calculated in the Function app is substituted for INT(Root) when this definition is evaluated.
• From other definitions
You could, for example, define F3(X)as F1(X)*F2(X).
Evaluate a dependent definition
If you have a dependent definition—that is, one defined in terms of another definition—you can combine all the definitions into one by evaluating the dependent definition.
1. Select the dependent expression.
2. Tap .
Consider the example at the right. Notice that F3(X)is defined in terms of two other functions. It is a dependent definition and can be evaluated.
If you highlight F3(X)and tap , F3(X)becomes 2* X2+X+ 2 *(X2–1).
Select or deselect a definition to explore
In the Advanced Graphing, Function, Parametric, Polar, Sequence, and Solve apps you can enter up to 10 definitions.
However, only those definitions that are selected in Symbolic view will be plotted in Plot view and evaluated in Numeric view.
You can tell if a definition is selected by the tick (or checkmark) beside it. A checkmark is added by default as soon as you create a definition. So if you don’t want to plot or evaluate a particular definition, highlight it and tap . (Do likewise if you want to re-select a deselected function.)
Choose a color for plots
Each function and open sentence can be plotted in a different color. If you want to change the default color of a plot:
1. Tap the colored square to the left of the function’s definition.
You can also select the square by pressing E while the definition is selected. Pressing E moves the selection from the definition to the colored square and from the colored square to the definition.
2. tap .
3. Select the desired color from the color-picker.
Delete a definition
To delete a single definition:
1. Tap once on it (or highlight it using the cursor keys).
2. Press C.
To delete all the definitions:
1. Press SJ.
2. Tap or press E to confirm your intention.