[petsc-users] Fwd: MatZeroRowsColumns for mpibaij

[Matthew Knepley]

On Wed, Oct 30, 2013 at 9:19 PM, Rhodri Davies <rhodri.davies at anu.edu.au>wrote:

>  Dear all,
>
>  Would you mind giving us an update on your thoughts re: this question?
> We're very keen to be able to use such functionally and it would be good to
> know if you're looking into this / have any suggestions?
>

I looked at the code. It does not look hard to make a MPIBAIJ version.
Since the scatter context for BAIJ is already exploded, most
of the MPIAIJ code goes straight through, it just a matter of handling the
blocking in a few places.

Here is what would be really helpful for us. Write a nice test. The code
would probably only take an hour of being careful. However,
the test assembly would be more. If you give us a nice test example for it,
writing it could happen pretty quickly.

  Thanks,

    Matt


> Best wishes,
>
>  Rhodri
>
>
> ---------------------------------------------------------------------------------------------------
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>
> Begin forwarded message:
>
>  *From: *Stephan Kramer <s.kramer at imperial.ac.uk>
>  *Subject: **Fwd: [petsc-users] MatZeroRowsColumns for mpibaij*
>  *Date: *31 October 2013 13:16:05 GMT+11:00
>  *To: *Rhodri Davies <rhodri.davies at anu.edu.au>
>
>
>
>
> -------- Original Message --------
> Subject: [petsc-users] MatZeroRowsColumns for mpibaij
> Date: Wed, 19 Jun 2013 13:22:31 +0100
> From: Stephan Kramer <s.kramer at imperial.ac.uk>
> To: PETSc users list <petsc-users at mcs.anl.gov>
>
> Dear all,
>
> We have found the MatZeroRowsColumns() routine to be very useful for
> lifting boundary conditions. Unfortunately we also found that it isn't
> implemented for matrix type mpibaij and we're quite keen on
> keeping the baij structure as it seems to give us significant savings for
> DG problems (in particular the blocked sor). I had a quick look at the
> implementation of MatZeroRowsColums_MPIAIJ but couldn't
> really estimate how hard it would be to do something similar for mpibaij
> (an implementation for seqbaij exists already). Is this something that's
> likely to be looked at in the future?
>
> Stephan
>
>
>
>
>
>
>


-- 
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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