[petsc-users] Is PCFactorSetZeroPivot() effective?

[Jozsef Bakosi]

On 06.01.2012 09:35, Jed Brown wrote:
> On Fri, Jun 1, 2012 at 9:27 AM, Jozsef Bakosi <jbakosi at lanl.gov> wrote:
> 
> > It seems like your suggestion
> >
> > -mg_coarse_redundant_pc_factor_zeropivot <2.22045e-14>: Pivot is
> > considered zero if less than (PCFactorSetZeroPivot)
> >
> > remedies the problem as I'm not getting the zeropivot error anymore. I
> > guess the problem was at the coarsest MG level. I set
> > mg_coarse_redundent_pc_factor to 1.0e-20 and that helped.
> >
> 
> Yes, but is the convergence good now?

Yeah. It seems like I get a similar convergence that I was getting on
lower core counts: 20-30 MG iterations on a 80 million cell mesh.

Jozsef