HP 48gII Graphing For Step Structure, « … start finish for counter loopclause increment Step … »

The FOR STEP Structure

The syntax for this structure is

«… start finish FOR counter loopclause increment STEP … »

FOR … STEP executes the loopclause sequence just like FOR … NEXT does — except that the program specifies the increment value for counter, rather than incrementing by 1. The loopclause is always executed at least once.

Syntax

Start

finish

FOR

loop-clause

increment

STEP

Flowchart

1:Start

2:finish

counter=start Store finish

Body of loop

1:increment

counter = counter + increment

Isyes

counter ≤ finish?

no

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 loopclause is execut ed — counter can appear within the loopclause. 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 »

RPL Programming 121