fpt Reference: CHANGE .EQ. FOR LOGICAL TO .EQV.

fpt and WinFPT Reference Manual - Command-line Commands

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CHANGE .EQ. FOR LOGICAL TO .EQV.

Syntax:

[DO NOT] CHANGE [.]EQ[.] FOR LOGICAL TO [.]EQV[.]
[DO NOT] CHANGE [.]EQ[.] TO [.]EQV[.] FOR LOGICALS

Function:

Expressions of the form L1 .EQ. L2 or L1 .NE. L2 where L1 and L2 are logical variables or expressions are changed to (L1 .EQV. L2) or (L1 .NEQV. L2). Note that the Fortran 77 standard requires the use of .EQV. and .NEQV.for logicals, and .EQ. and .NE.are not supported for logicals by some compilers, notably gfortran.

Note that the sub-expression around the original .EQ., ==, .NE. or /= operator is enclosed in parentheses. This is done because .EQ. and .NE. have higher operator precedence than .EQV. and .NEQV.. Thus, if lr, t and f are logical variables, t has the value .TRUE. and f has the value .FALSE., the expression:

lr = f .AND. t .EQ. t .AND. f

evaluates as f .AND. (t .EQ. t) .AND. f which is .FALSE..

The expression:

lr = f .AND. t .EQV. t .AND. f

evaluates as (f .AND. t) .EQV. (t .AND. f) which is .TRUE..

The insertion of the parentheses is made in fpt version 3.9-d and later. Thanks are due to Dan Leslie at Sector7 Inc. for pointing out the need for this change.

Where to Use this Command

Operating system command line	Yes
Configuration file, config.fsp	Yes
Specification (fsp) files, *.fsp	Yes
Interactively, to FPT> prompt	Yes
Interactive command files	Yes
Embedded in the Fortran code	No

Default

No change is made by default.