[petsc-users] ML and -pc_factor_shift_nonzero

[Barry Smith]

   -mg_coarse_pc_factor_shift_nonzero since it is the coarse level of  
the multigrid that is producing the zero pivot.

    Barry

On Apr 13, 2010, at 8:51 AM, Matthew Knepley wrote:

> On Tue, Apr 13, 2010 at 2:49 PM, <tribur at vision.ee.ethz.ch> wrote:
> Hi,
>
> using ML I got the error
>
> "[0]PETSC ERROR: Detected zero pivot in LU factorization"
>
> As recommended at http://www.mcs.anl.gov/petsc/petsc-as/documentation/troubleshooting.html 
> , I tried -pc_factor_shift_nonzero but it doesn't have the desired  
> effect using ML.
>
> How do I have to formulate the command line option? What does - 
> [level]_pc_factor_shift_nonzero mean? What other parallel  
> preconditioner could I try besides Hypre/Boomeramg or ML?
>
> This means the MG level, like 2. You can see all available options  
> using -help.
>
>   Matt
>
> Thanks in advance for your precious help,
>
> Kathrin
>
>
>
>
>
> -- 
> 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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