[petsc-users] MatGetSize for SeqBAIJ

[Matthew Knepley]

On Tue, Mar 1, 2016 at 10:56 AM, Manav Bhatia <bhatiamanav at gmail.com> wrote:

> Thanks. That means I am doing something goofy in setting up my matrix.
>
> I am trying to create a matrix with block size 2, and 3000 as the number
> of block rows/columns. So, I would expect an output of 6000x6000 from the
> following code, but I get 3000x3000. Is it the sequence of my function
> calls?
>
> Thanks,
> Manav
>
>
>
>     PetscErrorCode   ierr;
>     Mat              mat;
>     PetscInt m,n;
>
>     ierr = MatCreate(mpi_comm, &mat);
>     ierr = MatSetSizes(mat, 3000, 3000, 3000, 3000);
>

MatSetSizes also takes the number of rows, not blocks.

  Matt


>     ierr = MatSetType(mat, MATBAIJ);
>     ierr = MatSetBlockSize(mat, 2);
>     ierr = MatGetSize(mat, &m, &n);
>
>     std::cout << m << "  " << n << std::endl;
>
>
>
> On Mar 1, 2016, at 10:44 AM, Hong <hzhang at mcs.anl.gov> wrote:
>
> Manav:
>>
>>    Is MatGetSize for a SeqBAIJ matrix expected to return the number of
>> block rows and columns, or the total number of rows and columns (blocks
>> rows times block size)?
>>
>
> +  m - the number of global rows
> -  n - the number of global columns
> the total number of rows and columns (blocks rows times block size).
>
> Hong
>
>
>


-- 
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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