[petsc-users] issue with NullSpaceRemove in parallel

[Mohammad Mirzadeh]

Thanks Barry. That seems to have fixed it; I had a NAN somewhere in the RHS.

On Wed, Oct 5, 2016 at 11:18 PM, Barry Smith <bsmith at mcs.anl.gov> wrote:

>
>   The message "Scalar value must be same on all processes, argument # 2"
> comes up often when a Nan or Inf as gotten into the computation. The IEEE
> standard for floating point operations defines that Nan != Nan;
>
>   I recommend running again with -fp_trap this should cause the code to
> stop with an error message as soon as the Nan or Inf is generated.
>
>   Barry
>
>
>
>
> > On Oct 5, 2016, at 9:21 PM, Mohammad Mirzadeh <mirzadeh at gmail.com>
> wrote:
> >
> > Hi folks,
> >
> > I am trying to track down a bug that is sometimes triggered when solving
> a singular system (poisson+neumann). It only seems to happen in parallel
> and halfway through the run. I can provide detailed information about the
> actual problem, but the error message I get boils down to this:
> >
> > [0]PETSC ERROR: --------------------- Error Message
> --------------------------------------------------------------
> > [0]PETSC ERROR: Invalid argument
> > [0]PETSC ERROR: Scalar value must be same on all processes, argument # 2
> > [0]PETSC ERROR: See http://www.mcs.anl.gov/petsc/documentation/faq.html
> for trouble shooting.
> > [0]PETSC ERROR: Petsc Release Version 3.6.3, Dec, 03, 2015
> > [0]PETSC ERROR: ./two_fluid_2d on a linux named bazantserver1 by
> mohammad Wed Oct  5 21:14:47 2016
> > [0]PETSC ERROR: Configure options PETSC_ARCH=linux --prefix=/usr/local
> --with-clanguage=cxx --with-c-support --with-shared-libraries
> --download-hypre --download-metis --download-parmetis --download-ml
> --download-superlu_dist COPTFLAGS=" -O3 -march=native" CXXOPTFLAGS=" -O3
> -march=native" FOPTFLAGS=" -O3 -march=native"
> > [0]PETSC ERROR: #1 VecShift() line 1480 in /tmp/petsc-3.6.3/src/vec/vec/
> utils/vinv.c
> > [0]PETSC ERROR: #2 MatNullSpaceRemove() line 348 in
> /tmp/petsc-3.6.3/src/mat/interface/matnull.c
> > [0]PETSC ERROR: #3 KSP_RemoveNullSpace() line 207 in
> /tmp/petsc-3.6.3/include/petsc/private/kspimpl.h
> > [0]PETSC ERROR: #4 KSP_PCApply() line 243 in /tmp/petsc-3.6.3/include/
> petsc/private/kspimpl.h
> > [0]PETSC ERROR: #5 KSPInitialResidual() line 63 in
> /tmp/petsc-3.6.3/src/ksp/ksp/interface/itres.c
> > [0]PETSC ERROR: #6 KSPSolve_BCGS() line 50 in
> /tmp/petsc-3.6.3/src/ksp/ksp/impls/bcgs/bcgs.c
> > [0]PETSC ERROR: #7 KSPSolve() line 604 in /tmp/petsc-3.6.3/src/ksp/ksp/
> interface/itfunc.c
> >
> > I understand this is somewhat vague question, but any idea what could
> cause this sort of problem? This was on 2 processors. The same code runs
> fine on a single processor. Also the solution seems to converge fine on
> previous iterations, e.g. this is the convergence info from the last
> iteration before the code breaks:
> >
> >   0 KSP preconditioned resid norm 6.814085878146e+01 true resid norm
> 2.885308600701e+00 ||r(i)||/||b|| 1.000000000000e+00
> >   1 KSP preconditioned resid norm 3.067319980814e-01 true resid norm
> 8.480307326867e-02 ||r(i)||/||b|| 2.939133555699e-02
> >   2 KSP preconditioned resid norm 1.526405979843e-03 true resid norm
> 1.125228519827e-03 ||r(i)||/||b|| 3.899855008762e-04
> >   3 KSP preconditioned resid norm 2.199423175998e-05 true resid norm
> 4.232832916628e-05 ||r(i)||/||b|| 1.467029528695e-05
> >   4 KSP preconditioned resid norm 5.382291463582e-07 true resid norm
> 8.438732856334e-07 ||r(i)||/||b|| 2.924724535283e-07
> >   5 KSP preconditioned resid norm 9.495525177398e-09 true resid norm
> 1.408250768598e-08 ||r(i)||/||b|| 4.880763077669e-09
> >   6 KSP preconditioned resid norm 9.249233376169e-11 true resid norm
> 2.795840275267e-10 ||r(i)||/||b|| 9.689917655907e-11
> >   7 KSP preconditioned resid norm 1.138293762641e-12 true resid norm
> 2.559058680281e-12 ||r(i)||/||b|| 8.869272006674e-13
> >
> > Also, if it matters, this is using hypre as PC and bcgs as KSP.
> >
> > Thanks
>
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.mcs.anl.gov/pipermail/petsc-users/attachments/20161006/5d996433/attachment.html>