Tells the compiler that single-precision constants assigned to double-precision variables should be evaluated in double precision.
Windows: Floating-Point > Extend Precision of Single-Precision Constants
Linux: None
Mac OS X: Floating-Point > Extend Precision of Single-Precision Constants
IA-32, Intel® 64, IA-64 architectures
Linux and Mac OS X: | -fpconstant -nofpconstant |
Windows: | /fpconstant /nofpconstant |
None
nofpconstant |
Single-precision constants assigned to double-precision variables are evaluated in single precision according to Fortran 95/90 Standard rules. |
This option tells the compiler that single-precision constants assigned to double-precision variables should be evaluated in double precision.
This is extended precision. It does not comply with the Fortran 95/90 standard, which requires that single-precision constants assigned to double-precision variables be evaluated in single precision.
It allows compatibility with FORTRAN 77, where such extended precision was allowed. If this option is not used, certain programs originally created for FORTRAN 77 compilers may show different floating-point results because they rely on the extended precision for single-precision constants assigned to double-precision variables.
None
In the following example, if you specify fpconstant, identical values are assigned to D1 and D2. If you omit fpconstant, the compiler will obey the Fortran 95/90 Standard and assign a less precise value to D1:
REAL (KIND=8) D1, D2
DATA D1 /2.71828182846182/ ! REAL (KIND=4) value expanded to double
DATA D2 /2.71828182846182D0/ ! Double value assigned to double