[MPI3 Fortran] Deprecate mpif.h?
Bill Long
longb at cray.com
Mon Mar 8 10:20:55 CST 2010
Rolf Rabenseifner wrote:
> I want to point here to a technical problem with the nice section
> MPI-2.2 482:39-484:18 "Problems Due to Data Copying and Sequence Association"
>
> I've done a test with assumed-shape and assumed-size formal
> arguments as buffer and using a strided actual argument when calling the
> routine (e.g. MPI_IRECV).
>
> With assumed-size, the compiler did call-by-in-and-out-copy,
> with assumed-shape, the compiler did call-by-reference.
Just to avoid possible confusion, the assumed-size case (around since
f77) is typically done with simple call-by-reference, whereas a case
with an assumed-shape actual argument causes copy-in/copy-out if the
associated dummy is not assumed-shape. Indeed, copy-in does not work
for an assumed-size actual since you don't know the size. I realize
that this was just a wording slip (Rolf clearly knows the right ideas),
but it was what prompted me to write up the terminology summary
yesterday.
Cheers,
Bill
--
Bill Long longb at cray.com
Fortran Technical Support & voice: 651-605-9024
Bioinformatics Software Development fax: 651-605-9142
Cray Inc./Cray Plaza, Suite 210/380 Jackson St./St. Paul, MN 55101
More information about the mpiwg-fortran
mailing list