Intel Fortran Language Reference - NCI National Facility

Execution Control 7
Form
Example
block1a INAVG = INAVG + 1
ELSE
ELSE
block1b OUTAVG = OUTAVG + 1
END IF
END IF
ELSE
ELSE
block2 OUTRAN = OUTRAN + 1
END IF
END IF
If A is less than 100, the code immediately following the IF is executed. This code contains a
nested IF construct. If the absolute value of A minus AVG is less than or equal to 5, block1a is
executed. If the absolute value of A minus AVG is greater than 5, block1b is executed.
If A is greater than or equal to 100, block2 is executed, and the nested IF construct (in block1) is
not executed.
The following example shows a named IF construct:
BLOCK_A: IF (D > 0.0) THEN ! Initial statement for named construct
RADIANS = ACOS(D)
! These two statements
DEGREES = ACOSD(D) ! form a block
END IF BLOCK_A
! Terminal statement for named construct
IF Statement
The IF statement conditionally executes one statement based on the value of a logical expression.
(This statement was called a logical IF statement in FORTRAN 77.)
The IF statement takes the following form:
IF (expr) stmt
expr
Is a scalar logical expression enclosed in parentheses.
stmt
Is any complete, unlabeled, executable Fortran statement, except for the following:
• A CASE, DO, IF, FORALL, or WHERE construct
• Another IF statement
• The END statement for a program, function, or subroutine
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