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Subject: [OMPI devel] Fortran 90 Interface
From: David Robertson (robertson_at_[hidden])
Date: 2009-01-21 17:25:23


I'm having a problem with MPI_COMM_WORLD in Fortran 90. I have tried
with OpenMPI versions 1.2.6, 1.2.8 and 1.3. Both versions are compiled
with the PGI 8.0-2 suite. I've run the program in a debugger and with
"USE mpi" and MPI_COMM_WORLD returns 'Cannot find name
"MPI_COMM_WORLD"'. If I use "include mpif.h" results are a little
better: MPI_COMM_WORLD returns 0 (the initial value assigned by
mpif-common.h). The MPI functions don't seem to be affected by the fact
that MPI_COMM_WORLD is unset or equal to 0. For example, the following
works just fine:

          CALL mpi_init (MyError)
          CALL mpi_comm_rank (MPI_COMM_WORLD, MyRank, MyError)
          CALL mpi_comm_size (MPI_COMM_WORLD, Nnodes, MyError)

even though, in the debugger, MPI_COMM_WORLD is unset or zero every step
of the way. However, when I try to us MPI_COMM_WORLD in a non MPI
standard function (Netcdf-4 in this case):

         status=nf90_create_par(TRIM(ncname), &
      & OR(nf90_clobber, nf90_netcdf4),
      & MPI_COMM_WORLD, info, ncid)

   I get the following error:

[daggoo:07640] *** An error occurred in MPI_Comm_dup
[daggoo:07640] *** on communicator MPI_COMM_WORLD
[daggoo:07640] *** MPI_ERR_COMM: invalid communicator
[daggoo:07640] *** MPI_ERRORS_ARE_FATAL (goodbye)

I have tried the exact same code compiled and run with MPICH2 (also PGI
8.0-2) and the problem does not occur.

If I have forgotten any details needed to debug this issue, please let
me know.

David Robertson