[petsc-users] Doubt in MPIPreallocation

[John Albequerque]

Dear Barry,
I am sorry I could not get you. I have also posted the entire error message
so that you could get a deeper insight into it.


Many thanks.

----
John Albequerque.










*========================================================================================Argument
out of range[0]PETSC ERROR: nnz cannot be greater than row length: local
row 0 value 1 rowlength 0[0]PETSC ERROR: See
http://www.mcs.anl.gov/petsc/documentation/faq.html
<http://www.mcs.anl.gov/petsc/documentation/faq.html> for trouble
shooting.[0]PETSC ERROR: Petsc Release Version 3.6.3, unknown [0]PETSC
ERROR: ./MatSparse on a linux-gnu-c-debug named John by johncfd Sat Feb 20
01:36:01 2016[0]PETSC ERROR: Configure options --with-cc=gcc --with-cxx=g++
--with-fc=gfortran --download-fblaslapack --download-mpich[0]PETSC ERROR:
#1 MatSeqAIJSetPreallocation_SeqAIJ() line 3567 in
/home//MyStuff/ClonedRepos/petsc/src/mat/impls/aij/seq/aij.c[0]PETSC ERROR:
#2 MatSeqAIJSetPreallocation() line 3539 in
/home/MyStuff/ClonedRepos/petsc/src/mat/impls/aij/seq/aij.c[0]PETSC ERROR:
#3 MatMPIAIJSetPreallocation_MPIAIJ() line 2835 in
/home/MyStuff/ClonedRepos/petsc/src/mat/impls/aij/mpi/mpiaij.c[0]PETSC
ERROR: #4 MatMPIAIJSetPreallocation() line 3532 in
/home/MyStuff/ClonedRepos/petsc/src/mat/impls/aij/mpi/mpiaij.c*
=========================================================================================


On Sat, Feb 20, 2016 at 12:35 AM, Barry Smith <bsmith at mcs.anl.gov> wrote:

>
> > On Feb 19, 2016, at 12:54 PM, John Albequerque <johncfdcfd at gmail.com>
> wrote:
> >
> > Jed, one more
> >
> > nnz cannot be greater than row length: local row 0 value 1 rowlength 0
>
>   Always send the entire error message, this provides the context to know
> what the hey is going on.
>
>   It looks like you set a matrix block (if you are using an MPI matrix on
> one process this could the the "off-diagonal" block)  which has no columns
> (hence row length is zero) but you claim you need to preallocate an entry
> (the 1).
>
>   Barry
>
> >
> > How do I deal with this error?
> >
> > Thanks.
> >
> > ----
> > John Albequerque.
> >
> >
> >
> > On Fri, Feb 19, 2016 at 8:17 PM, John Albequerque <johncfdcfd at gmail.com>
> wrote:
> > Thank you very much, I will try it.
> >
> >
> > Thanks
> >
> > ----
> > John Albequerque.
> >
> >
> >
> > On Fri, Feb 19, 2016 at 8:16 PM, Jed Brown <jed at jedbrown.org> wrote:
> > John Albequerque <johncfdcfd at gmail.com> writes:
> >
> > > So Jed, what you are suggesting is that I should set only the non-zero
> > > elements while using
> > > *  MatSetValues(A,(high-low),**idxm,nc,idxn,values,INSERT_*
> > >
> > > *VALUES);*
> > > And not mention the zero elements and for that I should loop over all
> local
> > > rows and then set each of the value.
> >
> > Yes.  The whole point of a sparse matrix is to spend no time or storage
> > on 0.0 entries.  If you allocate a dense matrix and store all the zeros,
> > you're just being inefficient relative to a dense format.
> >
> >
>
>
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