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•
Check out that the program call 0.5
`
2.5
`
0.5
`
@GLIS2
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:
J
1
#
1.5
#
0.5
`
Enter parameters 1 1.5 0.5
[‘]
@GLIS2
`
Enter the program name in level 1
„°LL
@)@RUN@ @@DBG@
Start the debugger.
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
The following program calculates the summation
∑
=
=
n
k
k
S
0
2
Using a DO…UNTIL…END loop:
«
0.
→
n S
«
DO n SQ S +
‘
S
‘
STO n 1 –
‘
n
‘
STO UNTIL
‘
n<0
‘
END S
“
S
”
→
TAG
»
»
