HP 39gs Loop commands

ZEROGROB	Creates a blank graphic with given width and height,
	and stores it in graphicname.
	ZEROGROB graphicname;width;height:

Loop commands

Loop hp allow a program to execute a routine repeatedly. The HP 39gs has three loop structures. The example programs below illustrate each of these structures incrementing the variable A from 1 to 12.

DO…UNTIL …END Do ... Until ... End is a loop command that executes the loop-clauserepeatedly until test-clausereturns 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
	DISP 3;A:
	UNTIL A == 12 END:
WHILE…	While ... Repeat ... End is a loop command that
REPEAT…	repeatedly evaluates test-clauseand executes loop-clause
END	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
	DISP 3;A:
	END:
FOR…TO…STEP	FOR name=start-expression TO end-expression
...END	[STEP increment];
	loop-clause	END
	FOR A=1 TO 12 STEP 1;

DISP 3;A:

END:

Programming 18-23