Setting tolerances for multigrid

[Matthew Knepley]

On 6/14/07, Knut Erik Teigen <knutert at stud.ntnu.no> wrote:
> Hello,
>
> How do I set the tolerances for the KSP solvers when using the
> DMMG routines without using command line arguments? It seems that
> I can use the argument -ksp_rtol on the command line, but in the code I
> can't use KSPSetTolerances since I don't have access to the KSP solver
> context?

You can use DMMGGetKSP() for the finest level, and dmmg[level]->ksp for
any others.

> Also, I see there is a reference to the function DMMGSetUseGalerkin
> in the source code, but I can't find the documentation for it.
> Does this function not exist yet? Again I would like to use
> -dmmg_galerkin, but setting it in the code instead of on the command
> line.

I think you want this:

http://www-unix.mcs.anl.gov/petsc/petsc-as/snapshots/petsc-current/docs/manualpages/DA/DMMGSetUseGalerkinCoarse.html

  Matt

> Regards,
> Knut Erik Teigen
>
>


-- 
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