[petsc-users] KSPsolve Problem

Tue Oct 14 14:57:51 CDT 2014

On Tue, Oct 14, 2014 at 2:52 PM, Sharp Stone <thronesf at gmail.com> wrote:

> Thank you for your replies.
>
> If I use -fp_trap, I still got the same type of errors as follows.
>
> [0]PETSC ERROR: VecValidValues() line 34 in
> /Users/GPL/local/PETSc/petsc-3.5.2/src/vec/vec/interface/rvector.c Vec
> entry at local location 0 is not-a-number or infinite at end of function:
> Parameter number 3
>
> If use -pc_type lu -ksp_type gmres options, I got the zero pivot error as
> you suspected... Is there a way that can solve this problem? Thank you very
> much!
>
> You are trying to solve a singular system:

https://www.khanacademy.org/math/precalculus/precalc-matrices/inverting_matrices/v/singular-matrices

Its not even clear what a solution would mean. I suggest starting with a
problem for which you know the answer.

   Matt

> [0]PETSC ERROR: --------------------- Error Message
> --------------------------------------------------------------
>
> [0]PETSC ERROR: Zero pivot in LU factorization:
> http://www.mcs.anl.gov/petsc/documentation/faq.html#ZeroPivot
>
> [0]PETSC ERROR: Zero pivot row 52 value 0 tolerance 2.22045e-14
>
> [0]PETSC ERROR: See http://www.mcs.anl.gov/petsc/documentation/faq.html
> for trouble shooting.
>
> [0]PETSC ERROR: Petsc Release Version 3.5.2, Sep, 08, 2014
>
> [0]PETSC ERROR: ./pStreamer on a arch-darwin-cxx-debug named
> host206-47.physci.fit.edu by GPL Tue Oct 14 15:49:50 2014
>
> [0]PETSC ERROR: Configure options --with-cc=gcc --with-cxx=g++
> --with-fc=gfortran --with-clanguage=cxx --download-fblaslapack
> --download-mpich
>
> [0]PETSC ERROR: #49 MatPivotCheck_none() line 622 in
> /Users/GPL/local/PETSc/petsc-3.5.2/include/petsc-private/matimpl.h
>
> [0]PETSC ERROR: #50 MatPivotCheck() line 641 in
> /Users/GPL/local/PETSc/petsc-3.5.2/include/petsc-private/matimpl.h
>
> [0]PETSC ERROR: #51 MatLUFactorNumeric_SeqAIJ_Inode() line 1713 in
> /Users/GPL/local/PETSc/petsc-3.5.2/src/mat/impls/aij/seq/inode.c
>
> [0]PETSC ERROR: #52 MatLUFactorNumeric() line 2894 in
> /Users/GPL/local/PETSc/petsc-3.5.2/src/mat/interface/matrix.c
>
> [0]PETSC ERROR: #53 PCSetUp_LU() line 152 in
> /Users/GPL/local/PETSc/petsc-3.5.2/src/ksp/pc/impls/factor/lu/lu.c
>
> [0]PETSC ERROR: #54 PCSetUp() line 902 in
> /Users/GPL/local/PETSc/petsc-3.5.2/src/ksp/pc/interface/precon.c
>
> [0]PETSC ERROR: #55 KSPSetUp() line 305 in
> /Users/GPL/local/PETSc/petsc-3.5.2/src/ksp/ksp/interface/itfunc.c
>
> [0]PETSC ERROR: #56 KSPSolve() line 417 in
> /Users/GPL/local/PETSc/petsc-3.5.2/src/ksp/ksp/interface/itfunc.c
>
> On Tue, Oct 14, 2014 at 3:18 PM, Barry Smith <bsmith at mcs.anl.gov> wrote:
>
>>
>>   I am guessing that the local solver is ILU(0) and that the ILU(0)
>> factorization is creating a NaN or Inf due to a zero pivot. What happens if
>> you run with the command line option -fp_trap  ?
>>
>>    Also if this is a small problem you can run with -mat_view to have it
>> display the factored matrix.
>>
>>   Barry
>>
>> On Oct 14, 2014, at 2:07 PM, Sharp Stone <thronesf at gmail.com> wrote:
>>
>> > Dear all,
>> >
>> > I'm trying to solve a linear system with petsc ksp solver. But after I
>> called the kspsolve routine, I always got the "Vec entry at local location
>> 0 is not-a-number or infinite at end of function" errors below. I checked
>> the matrix and the vectors, and they are all numbers (and zeros). Is this a
>> bug or I miss something? Thank you very much in advance!
>> >
>> > [0]PETSC ERROR: --------------------- Error Message
>> --------------------------------------------------------------
>> >
>> > [0]PETSC ERROR: Floating point exception
>> >
>> > [0]PETSC ERROR: Vec entry at local location 0 is not-a-number or
>> infinite at end of function: Parameter number 3
>> >
>> > [0]PETSC ERROR: See http://www.mcs.anl.gov/petsc/documentation/faq.html
>> for trouble shooting.
>> >
>> > [0]PETSC ERROR: Petsc Release Version 3.5.2, Sep, 08, 2014
>> >
>> > [0]PETSC ERROR: ./pStreamer on a arch-darwin-cxx-debug named
>> host206-47.physci.fit.edu by GPL Tue Oct 14 14:58:05 2014
>> >
>> > [0]PETSC ERROR: Configure options --with-cc=gcc --with-cxx=g++
>> --with-fc=gfortran --with-clanguage=cxx --download-fblaslapack
>> --download-mpich
>> >
>> > [0]PETSC ERROR: #12 VecValidValues() line 34 in
>> /Users/GPL/local/PETSc/petsc-3.5.2/src/vec/vec/interface/rvector.c
>> >
>> > [0]PETSC ERROR: #13 PCApply() line 442 in
>> /Users/GPL/local/PETSc/petsc-3.5.2/src/ksp/pc/interface/precon.c
>> >
>> > [0]PETSC ERROR: #14 KSP_PCApply() line 230 in
>> /Users/GPL/local/PETSc/petsc-3.5.2/include/petsc-private/kspimpl.h
>> >
>> > [0]PETSC ERROR: #15 KSPSolve_PREONLY() line 26 in
>> /Users/GPL/local/PETSc/petsc-3.5.2/src/ksp/ksp/impls/preonly/preonly.c
>> >
>> > [0]PETSC ERROR: #16 KSPSolve() line 459 in
>> /Users/GPL/local/PETSc/petsc-3.5.2/src/ksp/ksp/interface/itfunc.c
>> >
>> > [0]PETSC ERROR: #17 PCApply_BJacobi_Singleblock() line 675 in
>> /Users/GPL/local/PETSc/petsc-3.5.2/src/ksp/pc/impls/bjacobi/bjacobi.c
>> >
>> > [0]PETSC ERROR: #18 PCApply() line 440 in
>> /Users/GPL/local/PETSc/petsc-3.5.2/src/ksp/pc/interface/precon.c
>> >
>> > [0]PETSC ERROR: #19 KSP_PCApply() line 230 in
>> /Users/GPL/local/PETSc/petsc-3.5.2/include/petsc-private/kspimpl.h
>> >
>> > [0]PETSC ERROR: #20 KSPInitialResidual() line 56 in
>> /Users/GPL/local/PETSc/petsc-3.5.2/src/ksp/ksp/interface/itres.c
>> >
>> > [0]PETSC ERROR: #21 KSPSolve_BCGS() line 50 in
>> /Users/GPL/local/PETSc/petsc-3.5.2/src/ksp/ksp/impls/bcgs/bcgs.c
>> >
>> >
>> > [0]PETSC ERROR: #22 KSPSolve() line 459 in
>> /Users/GPL/local/PETSc/petsc-3.5.2/src/ksp/ksp/interface/itfunc.c
>> >
>> >
>> > --
>> > Best regards,
>> >
>>
>>
>
>
> --
> Best regards,
>
> Feng
>

-- 
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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