Texas Instruments Titanium TI-89, Руководство пользователя, Страница: 574 / 977

Programming 571
• You can create functions that expand on the TI-89 Titanium’s built-in functions. You
can then use the new functions the same as any other function.
• Functions return values that can be graphed or entered in a table; programs cannot.
• You can use a function (but not a program) within an expression. For example:
3
ù
func1(3)
is valid, but not
3
ù
prog1(3)
.
• Because you pass arguments to a function, you can write generic functions that are
not tied to specific variable names.
Note:
You can create a function from the Home screen, but the Program Editor is more
convenient for complex, multi-line functions.
Differences Between Functions and Programs
This guidebook sometimes uses the word command as a generic reference to
instructions and functions. When writing a function, however, you must differentiate
between instructions and functions.
A user-defined function:
• Can use the following instructions only. Any others are invalid.
Cycle
For...EndFor
Lbl
Return Define
Goto
Local
While...EndWhile Exit
If...EndIf
(all forms)
Loop...EndLoop
!
(
§
key)