HP 50g User Manual page 695

With the cursor
statement that will activate the IF construct when the program is executed.
Example: Type in the following program:
IF 'x<3' THEN 'x^2' EVAL END "Done" MSGBOX » »
« «
x
and save it under the name 'f1'. Press J and verify that variable @@@f1@@@ is
indeed available in your variable menu. Verify the following results:
@@@f1@@@ Result: 0
0
3.5 @@@f1@@@ Result: no action
These results confirm the correct operation of the IF...THEN...END construct.
The program, as written, calculates the function f
output otherwise).
The IF...THEN...ELSE...END construct
The IF...THEN...ELSE...END construct permits two alternative program flow
paths based on the truth value of the logical_statement. The general format of
this construct is:
IF logical_statement THEN program_statements_if_true ELSE
The operation of this construct is as follows:
1. Evaluate logical_statement.
2. If logical_statement is true, perform program statements_if_true and
continue program flow after the END statement.
3. If logical_statement is false, perform program statements_if_false and
continue program flow after the END statement.
To produce an IF...THEN...ELSE...END construct directly on the stack, use:
This will create the following input in the stack:
in front of the IF statement prompting the user for the logical
program_statements_if_false END.
„°@) @ BRCH@ ‚ @) @ IF@@
1.2 @@@f1@@@ Result: 1.44
10 @@@f1@@@ Result: no action
2
(x) = x
1
, if x < 3 (and not
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