[petsc-users] KSPsolve Problem

Tue Oct 14 15:40:55 CDT 2014

  Is the matrix suppose to be singular for the problem you are solving? Perhaps the boundary conditions are incomplete or wrong?

  Barry

On Oct 14, 2014, at 2:57 PM, Matthew Knepley <knepley at gmail.com> wrote:

> 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