Zero Pivot Row in LU Factorization

[Barry Smith]

   KSP *subksp;

    KSPGetPC(ksp,pc)
    PCBJacobiGetSubKSP(pc,&n,PETSC_NULL,&subksp)
    KSPGetPC(subksp[0],&subpc);
    PCFactorSetxxxxxx(subpc, ....

   Barry


On Nov 25, 2007, at 1:10 PM, Tim Stitt 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)
>