Hello everyone, I am using mat_view_info to see the matrix information in ksp/ksp/ex2.c: http://www.mcs.anl.gov/petsc/petsc-current/src/ksp/ksp/examples/tutorials/ex2.c.html
When I use single processor, I see two matrix-objects. One is the operator A, but what's the other one? It seems that the other one (always in seqaij or seqsbaij format) is from KSPSolve. What's the purpose of that matrix object? If I try two processors, I see five matrix-objects (more confused). Can you help me understand where these "five" matrices come from? Thanks. Best, Xiangdong Here is the script: ----------------------- ./ex2 -mat_view_info Matrix Object: 1 MPI processes type: seqaij rows=56, cols=56 total: nonzeros=250, allocated nonzeros=280 total number of mallocs used during MatSetValues calls =0 not using I-node routines Matrix Object: 1 MPI processes type: seqsbaij rows=56, cols=56 package used to perform factorization: petsc total: nonzeros=153, allocated nonzeros=153 total number of mallocs used during MatSetValues calls =0 block size is 1 Norm of error 0.000156044 iterations 6 -------------------------------- mpirun -np 2 ./ex2 -mat_view_info Matrix Object: 2 MPI processes type: mpiaij rows=56, cols=56 total: nonzeros=250, allocated nonzeros=560 total number of mallocs used during MatSetValues calls =0 not using I-node (on process 0) routines Matrix Object: 1 MPI processes type: seqaij rows=28, cols=28 total: nonzeros=118, allocated nonzeros=118 total number of mallocs used during MatSetValues calls =0 not using I-node routines Matrix Object: 1 MPI processes type: seqsbaij rows=28, cols=28 package used to perform factorization: petsc total: nonzeros=73, allocated nonzeros=73 total number of mallocs used during MatSetValues calls =0 block size is 1 Matrix Object: 1 MPI processes type: seqaij rows=28, cols=28 total: nonzeros=118, allocated nonzeros=118 total number of mallocs used during MatSetValues calls =0 not using I-node routines Matrix Object: 1 MPI processes type: seqsbaij rows=28, cols=28 package used to perform factorization: petsc total: nonzeros=73, allocated nonzeros=73 total number of mallocs used during MatSetValues calls =0 block size is 1 Norm of error 0.000411674 iterations 7