When viewing a MATMPIAIJ on a communicator of size>1, one can see something like this (in an ASCII viewer): Matrix Object: 1 MPI processes type: mpiaij row 0: (0, -8.32667e-17 + 0.4 i) (1, -1) (2, -1) row 1: (0, -1) (1, -8.32667e-17 + 0.4 i) (3, -1) (8, -1) row 2: (0, -1) (2, -8.32667e-17 + 0.4 i) (3, -1) (4, -1)
That may be a bit confusing, since the matrix one is trying to view has more than 1 ranks. This is, of course, the result of the way MatView is implemented: pull the distributed matrix into an MPIAIJ that lives on a communicator of size 1 containing the rank 0 of the original comm, then view that auxiliary matrix. Should we try to print the original comm size here, instead of "1 MPI processes"? That can be easily done by composing the original matrix with the auxiliary one and extracting it to check the comm size in MatView_SeqXXX. Alternatively, we could attach just the original comm size to the auxiliary Mat. Or am I the only one bothered by this? Dmitry. -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.mcs.anl.gov/pipermail/petsc-dev/attachments/20120606/f778b671/attachment.html>