[mpich-discuss] Fortran integer support 4/8-bytes

[Jed Brown]

On Fri, Jun 8, 2012 at 4:30 AM, Reuti <reuti at staff.uni-marburg.de> wrote:

> Aha, I thought the supported data types were meant.
>
> For a Fortran integer 64 interface I had to compile a special version for
> an application called Dirac:
>
>
> http://wiki.chem.vu.nl/dirac/index.php/How_to_build_MPI_libraries_for_64-bit_integers
>

But this only changes the size of Fortran integer. It doesn't change C int
and in practice, the Fortran bindings call C bindings that use C int, so
larger values would be truncated. So you can get 8-byte integers in Fortran
if you're determined, but it doesn't circumvent the 2^31 limit.

"Do these permit values greater than what is representable in a 4-byte
integer or does the lower level implementation in C preclude the use
of arguments greater than 2^31?"
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