> On Apr 24, 2015, at 1:05 PM, Danyang Su <[email protected]> wrote:
> 
> Hi All,
> 
> One of my case crashes because of floating point exception when using 4 
> processors, as shown below. But if I run this case with 1 processor, it works 
> fine. I have tested the codes with around 100 cases up to 768 processors, all 
> other cases work fine. I just wonder if this kind of error is caused because 
> of NaN in jacobi matrix, RHS or preconditioner?

   Yes, almost for sure it is one of these places.

   First run the bad case with -fp_trap  if all goes well you'll see the 
function where the FPE is generated. Then run also with -start_in_debugger and
type cont in all four debugger windows. When the FPE happens the debugger 
should stop showing exactly where the FPE happens.

  Barry

> I can check all the entries of jacobi matrix to see if the value is valid, 
> but this seems not a good idea as it takes a long time to reach this point. 
> If I restart the simulation from a specified time (e.g., 7.685 in this case), 
> then the error does not occur.
> 
> Would you please give me any suggestion on debugging this case?
> 
> Thanks and Regards,
> 
> Danyang
> 
> 
> timestep:    2730 time: 7.665E+00 years   delt: 1.000E-02 years iter:  1 
> max.sia: 0.000E+00 tol.sia: 0.000E+00
> timestep:    2731 time: 7.675E+00 years   delt: 1.000E-02 years iter:  1 
> max.sia: 0.000E+00 tol.sia: 0.000E+00
> timestep:    2732 time: 7.685E+00 years   delt: 1.000E-02 years iter:  1 
> max.sia: 0.000E+00 tol.sia: 0.000E+00
> timestep:    2733 time: 7.695E+00 years   delt: 1.000E-02 years iter:  1 
> max.sia: 0.000E+00 tol.sia: 0.000E+00
> timestep:    2734 time: 7.705E+00 years   delt: 1.000E-02 years iter:  1 
> max.sia: 0.000E+00 tol.sia: 0.000E+00
> Reduce time step for reactive transport
> timestep:    2734 time: 7.700E+00 years   delt: 5.000E-03 years iter:  1 
> max.sia: 0.000E+00 tol.sia: 0.000E+00
> Reduce time step for reactive transport
> timestep:    2734 time: 7.697E+00 years   delt: 2.500E-03 years iter:  1 
> max.sia: 0.000E+00 tol.sia: 0.000E+00
> [1]PETSC ERROR: --------------------- Error Message 
> --------------------------------------------------------------
> [1]PETSC ERROR: Floating point exception
> [2]PETSC ERROR: --------------------- Error Message 
> --------------------------------------------------------------
> [2]PETSC ERROR: Floating point exception
> [2]PETSC ERROR: Vec entry at local location 0 is not-a-number or infinite at 
> end of function: Parameter number 3
> [2]PETSC ERROR: See http://www.mcs.anl.gov/petsc/documentation/faq.html for 
> trouble shooting.
> [2]PETSC ERROR: Petsc Release Version 3.5.2, Sep, 08, 2014
> [2]PETSC ERROR: [1]PETSC ERROR: Vec entry at local location 0 is not-a-number 
> or infinite at end of function: Parameter number 3
> [1]PETSC ERROR: See http://www.mcs.anl.gov/petsc/documentation/faq.html for 
> trouble shooting.
> [1]PETSC ERROR: Petsc Release Version 3.5.2, Sep, 08, 2014
> [1]PETSC ERROR: ../min3p_thcm_petsc_dbg on a linux-gnu-dbg named nwmop by dsu 
> Thu Apr 23 15:38:52 2015
> [1]PETSC ERROR: Configure options PETSC_ARCH=linux-gnu-dbg --with-cc=gcc 
> --with-cxx=g++ --with-fc=gfortran --download-fblaslapack --download-mpich 
> --download-mumps --download-hypre --download-superlu_dist --download-metis 
> --download-parmetis --download-scalapack
> [1]PETSC ERROR: #1 VecValidValues() line 34 in 
> /home/dsu/Soft/PETSc/petsc-3.5.2/src/vec/vec/interface/rvector.c
> ../min3p_thcm_petsc_dbg on a linux-gnu-dbg named nwmop by dsu Thu Apr 23 
> 15:38:52 2015
> [2]PETSC ERROR: Configure options PETSC_ARCH=linux-gnu-dbg --with-cc=gcc 
> --with-cxx=g++ --with-fc=gfortran --download-fblaslapack --download-mpich 
> --download-mumps --download-hypre --download-superlu_dist --download-metis 
> --download-parmetis --download-scalapack
> [2]PETSC ERROR: #1 VecValidValues() line 34 in 
> /home/dsu/Soft/PETSc/petsc-3.5.2/src/vec/vec/interface/rvector.c
> [2]PETSC ERROR: [1]PETSC ERROR: #2 PCApply() line 442 in 
> /home/dsu/Soft/PETSc/petsc-3.5.2/src/ksp/pc/interface/precon.c
> [1]PETSC ERROR: #2 PCApply() line 442 in 
> /home/dsu/Soft/PETSc/petsc-3.5.2/src/ksp/pc/interface/precon.c
> [2]PETSC ERROR: #3 KSP_PCApply() line 230 in 
> /home/dsu/Soft/PETSc/petsc-3.5.2/include/petsc-private/kspimpl.h
> #3 KSP_PCApply() line 230 in 
> /home/dsu/Soft/PETSc/petsc-3.5.2/include/petsc-private/kspimpl.h
> [1]PETSC ERROR: #4 KSPInitialResidual() line 63 in 
> /home/dsu/Soft/PETSc/petsc-3.5.2/src/ksp/ksp/interface/itres.c
> [2]PETSC ERROR: #4 KSPInitialResidual() line 63 in 
> /home/dsu/Soft/PETSc/petsc-3.5.2/src/ksp/ksp/interface/itres.c
> [1]PETSC ERROR: #5 KSPSolve_GMRES() line 234 in 
> /home/dsu/Soft/PETSc/petsc-3.5.2/src/ksp/ksp/impls/gmres/gmres.c
> [2]PETSC ERROR: #5 KSPSolve_GMRES() line 234 in 
> /home/dsu/Soft/PETSc/petsc-3.5.2/src/ksp/ksp/impls/gmres/gmres.c
> [2]PETSC ERROR: #6 KSPSolve() line 459 in 
> /home/dsu/Soft/PETSc/petsc-3.5.2/src/ksp/ksp/interface/itfunc.c
> [1]PETSC ERROR: #6 KSPSolve() line 459 in 
> /home/dsu/Soft/PETSc/petsc-3.5.2/src/ksp/ksp/interface/itfunc.c
> ^C[mpiexec@nwmop] Sending Ctrl-C to processes as requested
> [mpiexec@nwmop] Press Ctrl-C again to force abort

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