Toon Knapen wrote:
Fortran LOGICAL


could you elaborate?
Toon,

There is no universally-agreed Fortran convention for how .TRUE. and .FALSE. boolean values are represented and how a value is checked for .TRUE. and .FALSE.

Some Fortran implementations use  0 for .FALSE. and 1  for .TRUE. (they may test for .TRUE. as being NON-ZERO)
Some Fortran implementations use  0 for .FALSE. and -1 for .TRUE. (they may test for .TRUE. as being NEGATIVE)
Some Fortran implementations use -1 for .FALSE. and +1 for .TRUE. (they may test for POSITIVE .TRUE. and NEGATIVE .FALSE.)

Checkout the PGI and ABSOFT Fortran compilers for example.

Regards
       Neil
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