[petsc-users] ML and -pc_factor_shift_nonzero

Matthew Knepley knepley at gmail.com
Tue Apr 13 08:51:55 CDT 2010

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


> 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
-- Norbert Wiener
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