Hi Stefano, > I'm observing a very strange behaviour using > PetscWrappers::MPI:sparse_matrix. Namely, if I run two times using nprocs =1 > I obtain (as expected) the same matrix_output (except for matrix names in > matlab_output but it is right). But when using np > 1, matrix values are > different: not only between nprocs = 1 and nprocs > 1 runs, but also between > runs with same nprocs value greater than one: it seems it prints out the > matrix before the PETSc assembly process has terminated (and not all cached > values as been transferred into PETSc Mat) . Is it normal?
Do you print out the data after the call to compress()? Also note that the matrix depends on the number of processes because the degrees of freedom are ordered in a different way. The matrix should be the same with the same number of processes of course. Is this also happening in step-18 for you? Anything interesting happening in debug mode or running with valgrind? Can you construct a minimal example that shows this? -- Timo Heister http://www.math.tamu.edu/~heister/ _______________________________________________ dealii mailing list http://poisson.dealii.org/mailman/listinfo/dealii
