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Re: gfortran vs ifort
Girish Kulkarni wrote:
>
> Surprisingly, results with `ifort -O0` (v 10.1 on amd64) do not match
> with `gfortran -O0` (v 4.1.2 on amd64) for the code that I described
> earlier. --
>
> http://gcc.gnu.org/ml/fortran/2009-05/msg00406.html
>
> Moreover, results with `gfortran -O0` (v 4.1.2 on amd64) *do not
> match* with `gfortran -O0` (v 4.3.2-1.1 on i386).
>
ifort -O0 defaults to the equivalent of -mfpmath=387, even in the 64-bit
version, as does gfortran for i386, while I believe gfortran for x86_64
defaults to -mfpmath=sse or -msse2. This shouldn't be so surprising.
Setting -O0 doesn't relieve you from paying attention to these factors,
although I think you are changing the subject frivolously.
gfortran 4.1.2 is unacceptably out of date, and shouldn't be compared with
a recent version, although that may not be your issue here.
OK, maybe you shouldn't trust any source code of questionable origin.