The Do Construct - HP 50g User Manual

Example – generate a list of numbers using a FOR...STEP construct
Type in the program:
«
xs xe dx
dx STEP n
and store it in variable @GLIS2.
Check out that the program call
produces the list {0.5 1. 1.5 2. 2.5}.
To see step-by-step operation use the program DBUG for a short list, for
example:
J1 # 1.5 # 0.5 `
['] @GLIS2 `
„°LL @) @ RUN@ @@DBG@
Use @SST @ to step into the program and see the detailed operation of each
command.

The DO construct

The general structure of this command is:
DO program_statements UNTIL logical_statement END
The DO command starts an indefinite loop executing the program_statements
until the logical_statement returns FALSE (0). The logical_statement must
contain the value of an index whose value is changed in the
program_statements.
Example 1 - This program produces a counter in the upper left corner of the
screen that adds 1 in an indefinite loop until a keystroke (press any key) stops
the counter: 0 DO DUP 1 DISP 1 + UNTIL KEY END DROP »
«
Command KEY evaluates to TRUE when a keystroke occurs.
Example 2 – calculate the summation S using a DO...UNTIL...END construct
«
xe xs – dx / ABS 1. +
LIST » » »
n
0.5 ` 2.5 ` 0.5 ` @GLIS2
Enter parameters 1 1.5 0.5
Enter the program name in level 1
Start the debugger.
«
xs xe FOR x x
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