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Subject: [OMPI users] MPI_Cart_rank: Out-of-range coordinates are erroneous for non-periodic dimensions
From: Atle Rudshaug (atle_at_[hidden])
Date: 2009-01-07 03:08:43


I am trying to find the neighbor ranks in a 3D cartesian communicator. I
use MPI_Cart_shift for 6 of them, but for the 12 diagonals I tried to
use MPI_Cart_rank. However, only x-direction is periodic and my program
crashed because of out-of-range coordinates. Then I found something
strange in some MPICH documentation:

"Out-of-range coordinates are erroneous for non-periodic dimensions .
Versions of MPICH before 1.2.2 returned MPI_PROC_NULL for the rank in
this case."

Why doesn't it anymore? Is this the same for OpenMPI? I expected it to
return MPI_PROC_NULL which would make things much easier.

- Atle