[petsc-users] Questions for MatSolve

[Matthew Knepley]

On Tue, Jul 19, 2016 at 8:17 PM, Eduardo Jourdan <eduardojourdan92 at gmail.com
> wrote:

> Hi all,
>
> I would like to perform a specific number (for instance 4 of forward and
> backward sweeps with a seqaij matrix with block size 4, vectors b and x.
> Also, I need to do this same procedure with another matrix seqaij block
> size 16. I would appreciate if someone knows the best way to do it.
>

It sounds like you want PCSOR and PCApply, not MatSolve.

  Thanks,

     Matt


> 1 - I've been trying to use MatSolve. For the bs=4 it seems to work, but
> with the other matrix with bs=16 the residue diverges. When I call
> matConvert to convert the later matrix for a seqbaij with bs=16 the result
> changes and the linear residue is reduced. It is supposed to happen or it
> is more possible that i am doing something wrong?
>
> 2 - MatSolve for seqbaij and seqaij with the same block sizes gives the
> same results in terms of solution (not performace, memory) ?
>
> 3 - Can do I do a specific number of sweeps as told before with the KSP/PC
> interface?
>
> 4 - I saw the manual for the MatSolve and It says that it is for factored
> matrix. Can I use a matrix just after the MatAssembly calls?
>
> Best regards,
>
> Eduardo Jourdan
>



-- 
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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