Reference Guide

RPL Programming 1-21
The FOR  STEP Structure
The syntax for this structure is
« … start finish FOR counter loop-clause increment STEP … »
FOR … STEP executes the loop-clause sequence just like FOR … NEXT does — except that the program specifies
the increment value for counter, rather than incrementing by 1. The loop-clause is always executed at least once.
Syntax Flowchart
Start
finish
FOR
loop-clause
STEP
1:Start
2:finish
counter=start
Store finish
Body of loop
counter = counter +
increment
Is
counter ≤ finish?
yes
no
1:increment
increment
FOR  STEP Structure
FOR takes start and finish from the stack as the beginning and ending values for the loop counter, then creates the
local variable counter as a loop counter. Next, the loop-clause is executed — counter can appear within the loop-clause.
STEP takes the increment value from the stack and increments counter by that value. If the argument of STEP is an
algebraic or a name, it’s automatically evaluated to a number.
The increment value can be positive or negative. If the increment is positive, the loop is executed again if counter is
less than or equal to finish. If the increment is negative, the loop is executed if counter is greater than or equal to finish.
Otherwise, counter is purged and execution resumes following STEP. In the previous flowchart, the increment value
is positive.
To enter FOR  STEP in a program:
 Press !° %BRCH% … %FOR% .
Example: The following program places the squares of the integers 1, 3, 5, 7, and 9 on the stack:
« 1 9 FOR x x SQ 2 STEP »