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[Beowulf] Re: fftw2, mpi, from 32 bit to 64 and fortran

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Jason Riedy jason at acm.org
Fri Aug 1 12:29:08 PDT 2008


And Ricardo Reis writes:
> In a 64 bit machine the mpi version kaputs. Any thoughts?

I'd bet that you're calling MPI routines directly from your Fortran code
somewhere, and fftw is a red herring...  When calling MPI routines
directly from your Fortran code, be very, very careful about the
arguments being passed.  Many MPI routines stuff a pointer in a "large
enough" integer, but some of the MPI/Fortran "header" files make too
many assumptions about the particular compiler and flags in use.

You might want to use the ISO_C_BINDING module and the BIND(C,
NAME="...") gizmos to declare the specific routines you're using.

Jason



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