[petsc-dev] petsc_infinity and vecset

[Jason Sarich]

There's a floating point exception error showing up in the nightly builds,
only for some bounded TAO Fortran examples using
arch-opensolaris-misc_n-gage
<http://ftp.mcs.anl.gov/pub/petsc/nightlylogs/archive/2014/06/06/examples_next_arch-opensolaris-pkgs-opt_n-gage.log>


> > [0]PETSC ERROR:
> ------------------------------------------------------------------------
> > [0]PETSC ERROR: Caught signal number 8 FPE: Floating Point
> Exception,probably divide by zero
> > [0]PETSC ERROR: Try option -start_in_debugger or
> -on_error_attach_debugger
> > [0]PETSC ERROR: or see
> http://www.mcs.anl.gov/petsc/documentation/faq.html#valgrind[0]PETSC
> ERROR: or try http://valgrind.org on GNU/linux and Apple Mac OS X to find
> memory corruption errors
> > [0]PETSC ERROR: configure using --with-debugging=yes, recompile, link,
> and run
> > [0]PETSC ERROR: to get more information on the crash.
> > [0]PETSC ERROR: --------------------- Error Message
> --------------------------------------------------------------
> > [0]PETSC ERROR: Signal received
> > [0]PETSC ERROR: See http://www.mcs.anl.gov/petsc/documentation/faq.html
> for trouble shooting.
> > [0]PETSC ERROR: Petsc Development GIT revision: v3.4.4-6010-g43e530f
>  GIT Date: 2014-06-05 17:04:47 -0500
> > [0]PETSC ERROR: ./plate2f on a arch-opensolaris-pkgs-opt named n-gage by
> petsc Fri Jun  6 01:17:49 2014
> > [0]PETSC ERROR: Configure options --with-debugger=/bin/true
> --with-debugging=0 --download-mpich=1 --with-c2html=0 --download-cmake=1
> --download-metis=1 --download-parmetis=1 --download-triangle=1
> --download-superlu=1 --download-superlu_dist=1 --download-fblaslapack=1
> --download-scalapack=1 --download-mumps=1 --download-parms=1
> --download-sundials=1 --download-hypre=1 --download-suitesparse=1
> --download-chaco=1 --download-spai=1 --with-no-output
> -PETSC_ARCH=arch-opensolaris-pkgs-opt
> -PETSC_DIR=/export/home/petsc/petsc.clone
> > [0]PETSC ERROR: #1 User provided function() line 0 in  unknown file
> > application called MPI_Abort(MPI_COMM_WORLD, 59) - process 0
> > [cli_0]: aborting job:
> > application called MPI_Abort(MPI_COMM_WORLD, 59) - process 0
> >
> >
> ===================================================================================
> > =   BAD TERMINATION OF ONE OF YOUR APPLICATION PROCESSES
> > =   EXIT CODE: 59
> > =   CLEANING UP REMAINING PROCESSES
> > =   YOU CAN IGNORE THE BELOW CLEANUP MESSAGES
> >
> ===================================================================================
> /export/home/petsc/petsc.clone/src/tao/bound/examples/tutorials
> Possible problem with plate2f_1 stdout, diffs above


In setting up the blmvm algorithm, I want to create a vector of infinity
values using
VecSet(XL,PETSC_INIFINITY) , where PETSC_INFINITY is defined in petscmath.h
as PETSC_MAX_REAL/4.0, in this case 4.49423e+307

I think this should be fine, but VecSet automagically computes the norms of
this vector, invoking the product of XL->map->N * PETSC_INFINITY which
causes the floating point exception.

Is there a better way to prevent this than testing if
(PetscAbsScalar(alpha) > PETSC_REAL_MAX/N) then NORM =  PETSC_INFINITY ?

This error is reproducible with the following code.
Again, this only seems to break Fortran programs with
arch-opensolaris-misc_n-gage

      program inftest
      implicit none
#include "finclude/petscsys.h"
#include "finclude/petscvec.h"



      PetscErrorCode ierr
      Vec x


      call PetscInitialize(PETSC_NULL_CHARACTER,ierr)

      call VecCreateSeq(MPI_COMM_SELF,100,x,ierr)
      call VecSet(x,PETSC_INFINITY,ierr)

      call PetscFinalize(ierr)
      end program
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