Application Guide

Differences Between Functions and Programs
A function defined in the Program Editor is similar to the functions built into the
TI-Nspire™ Software.
• Functions must return a result, which can be graphed or entered in a table.
Programs do not return a result.
• You can use a function (but not a program) within an expression. For example: 3 ¦
func1(3) is valid, but not 3 ¦ prog1(3).
• You can run programs from Calculator and Notes applications only. However, you
can evaluate functions in Calculator, Notes, Lists & Spreadsheet, Graphs &
Geometry, and Data & Statistics.
• A function can refer to any variable; however, it can store a value to a local variable
only. Programs can store to local and global variables.
Note: Arguments used to pass values to a function are treated as local variables
automatically. If you want to store to any other variables, you must declare them
as Local from within the function.
• A function cannot call a program as a subroutine, but it can call another user-
defined function.
• You cannot define a program within a function.
• A function cannot define a global function, but it can define a local function.
Calling One Program from Another
One program can call another program as a subroutine. The subroutine can be external
(a separate program) or internal (included in the main program). Subroutines are
useful when a program needs to repeat the same group of commands at several
different places.
Calling a Separate Program
To call a separate program, use the same syntax that you use to run the program from
the entry line.
Defining and Calling an Internal Subroutine
To define an internal subroutine, use the Define command with Prgm...EndPrgm.
Because a subroutine must be defined before it can be called, it is a good practice to
define subroutines at the beginning of the main program.
Getting Started with the Program Editor 495