Loop Commands - HP 39G User Manual

REPLACE
SUB
ZEROGROB

Loop commands

DO...UNTIL
...END
WHILE...
REPEAT...
END
15-22
Replaces portion of graphic in graphicname1 with
graphicname2 , starting at position. REPLACE also works
for lists and matrices.
REPLACE graphicname1;(position);graphicname2:
Extracts a portion of the named graphic (or list or matrix), and
stores it in a new variable, name. The portion is specified by
position and positions.
SUB name;graphicname;(position);(positions):
Creates a blank graphic with given width and height, and
stores it in graphicname.
ZEROGROB graphicname;width;height:
Loop structures allow a program to execute a routine
repeatedly. The HP 39G/40G has three loop structures. The
example programs below illustrate each of these structures
incrementing the variable A from 1 to 12.
Do ... Until ... End is a loop structure that executes the loop-
clause repeatedly until test-clause returns a true (nonzero)
result. Because the test is executed after the loop-clause, the
loop-clause is always executed at least once. Its syntax is:
DO loop-clause UNTIL test-clause END
1 A:
DO A + 1 A
UNTIL A == 12
END
While ... Repeat ... End is a loop structure that repeatedly
evaluates test-clause and executes loop-clause sequence if the
test is true. Because the test-clause is executed before the
loop-clause, the loop-clause is not executed if the test is
initially false. Its syntax is:
WHILE test-clause REPEAT loop-clause END
1 A:
WHILE A < 12
REPEAT A+1 A
END
Programming