Zero Pivot Row in LU Factorization

[Matthew Knepley]

This is because on many processes I believe you are running Block-Jacobi
with LU on the diagonal blocks. It is easy for one of these blocks to
be singular.

   Matt

On Nov 25, 2007 1:10 PM, Tim Stitt <timothy.stitt at ichec.ie> wrote:
> I should also add that the code executes without this error when using 1
> processor...but then displays the error when running in parallel with
> more than one process.
>
> Tim Stitt wrote:
> > Hi all,
> >
> > Can anyone suggest ways of overcoming the following pivot error I keep
> > receiving in my PETSc code during a KSPSolve().
> >
> > [1]PETSC ERROR: Detected zero pivot in LU factorization
> > see
> > http://www.mcs.anl.gov/petsc/petsc-as/documentation/troubleshooting.html#ZeroPivot!
> >
> > [1]PETSC ERROR: Zero pivot row 1801 value 0.00102826 tolerance
> > 0.00165189 * rowsum 1.65189e+09!
> >
> > From checking the documentation....the error is in row 1801, which
> > means it is most likely not a matrix assembly issue?
> >
> > I tried the following prior to the solve with no luck either.....
> >
> > call KSPGetPC(ksp,pc,error)
> > call PCFactorSetShiftNonzero(pc,PETSC_DECIDE,error)
> >
>
> > Is there anything else I can try?
> >
> > Thanks,
> >
> > Tim.
> >
>
>
> --
> Dr. Timothy Stitt <timothy_dot_stitt_at_ichec.ie>
> HPC Application Consultant - ICHEC (www.ichec.ie)
>
> Dublin Institute for Advanced Studies
> 5 Merrion Square - Dublin 2 - Ireland
>
> +353-1-6621333 (tel) / +353-1-6621477 (fax)
>
>



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