Texas Instruments TI-89 User Manual

Page of 1008
Programming
 593
Lbl
 commands are local to the programs in which they are located. Therefore, a 
Goto
 
command in the calling program cannot branch to a label in a subroutine or vice versa.
Using Variables in a Program
Using Variables in a Program
Using Variables in a Program
Using Variables in a Program
Programs use variables in the same general way that you use them from the Home 
screen. However, the “scope” of the variables affects how they are stored and accessed.
Scope of Variables
Scope of Variables
Scope of Variables
Scope of Variables
Scope
Description
System (Global) 
Variables
Variables with reserved names that are created 
automatically to store data about the state of the 
calculator. For example, Window variables (xminxmax
yminymax, etc.) are globally available from any folder.
You can always refer to these variables by using the 
variable name only, regardless of the current folder.
A program cannot create system variables, but it can 
use the values and (in most cases) store new values.