[petsc-users] MATELEMENTAL MatSetValue( )

[Jed Brown]

Use MatGetOwnershipIS() and set only the entries in your owned rows and
columns.  What you're doing is nonscalable anyway because every process
is filling the global matrix.  If you want a cheap hack for small
problems on small numbers of cores, you can run your insertion loop on
only rank 0.

"Eric D. Robertson" <eric.robertson at cfdrc.com> writes:

> I am trying to multiply two dense matrices using the Elemental interface. I fill the matrix using MatSetValue( ) like below:
>
>  for ( i = 0; i < Matrix.M; i++){
>         for ( j = 0; j < Matrix.N; j++) {
>              PetscScalar temp = i + one + (j*three);
>              MatSetValue(Matrix.A, i, j, temp, INSERT_VALUES);
>
>       }
>    }
>
>
> However, I seem to get the following error:
>
> [0]PETSC ERROR: No support for this operation for this object type
> [0]PETSC ERROR: Only ADD_VALUES to off-processor entry is supported
>
> But if I use ADD_VALUES, I get a different matrix depending on the number of processors used. The entries become multiplied by the number of processors. How do I reconcile this?
>
>
> <redir.aspx?REF=hVEx-ekIltbV6NDJuYjzplTZG3ymEirNPcO9eR2dIGrvJzCyE4XTCAFtYWlsdG86ZXJpYy5yb2JlcnRzb25AY2ZkcmMuY29t>
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