Parallel partitioning of the matrix

[Matthew Knepley]

On Tue, Mar 31, 2009 at 3:58 PM, Nguyen, Hung V ERDC-ITL-MS <
Hung.V.Nguyen at usace.army.mil> wrote:

> All,
>
> I have a test case that each processor reads its owned part of matrix in
> csr
> format dumped out by CFD application.
> Note: the partitions of matrix were done by ParMetis.
>
> Code below shows how to insert data into PETSc matrix (gmap is globalmap).
> The solution from PETSc is very closed to CFD solution so I think it is
> correct.
>
> My question is whether the parallel partitioning of the matrix is
> determined
> by PETSc at runtime or is the same as ParMetis?
>
> Thank you,
>
> -hung
> ---
>      /* create a matrix object */
>        MatCreateMPIAIJ(PETSC_COMM_WORLD, my_own, my_own,M,M, mnnz,


       ^^^^^^^^^^

You have determined the partitioning right here.

   Matt


>
>                   PETSC_NULL, mnnz, PETSC_NULL, &A);
>
>      for(i =0; i < my_own; i++) {
>           int row = gmap[i];
>           for (j = ia[i]; j < ia[i+1]; j++) {
>             int col = ja[j];
>             jj = gmap[col];
>             MatSetValues(A,1,&row,1,&jj,&val[j], INSERT_VALUES);
>         }
>       }
> /* free temporary arrays */
>       free(val); free(ja); free(ia);
>
> /* assemble the matrix and vectors*/
>      MatAssemblyBegin(A, MAT_FINAL_ASSEMBLY);
>      MatAssemblyEnd(A, MAT_FINAL_ASSEMBLY);
>
>
>


-- 
What most experimenters take for granted before they begin their experiments
is infinitely more interesting than any results to which their experiments
lead.
-- Norbert Wiener
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