[petsc-users] early convergence failure

[Matthew Knepley]

On Wed, Dec 19, 2012 at 10:00 AM, Daniel Arndt
<daniel.arndt at stud.uni-goettingen.de> wrote:
>>> Thank you Barry for your suggestions.
>>> The error I get is now KSP_DIVERGED_INDEFINITE_PC. The matrix that I try
>>> to invert is actually symmetric and positive definite. I was not aware that
>>> this can lead to a indefinite preconditioner.
>
>>   Absolutely. Many preconditioners do not retain this feature even in
>> exact precision and with numerical effects it can even appear unexpected.
>>   By default BoomAMG doesn't retain this.
>
> Is there then a possibility to tell the BlockJacobi preconditioner to be
> positive definit as there is for the BoomerAMG preconditioner via
> -pc_hypre_boomeramg_relax_type_all symmetric-SOR/Jacobi?

Block-Jacobi is just a container. You can choose the inner solver to
respect this.

   Matt

> Bests
> Daniel
>
>



--
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