[petsc-users] Zeroed solution after 0 iterations

[John Mousel]

Thanks Barry.

On Wed, Apr 13, 2016 at 12:42 PM, Barry Smith <bsmith at mcs.anl.gov> wrote:

>
>    John,
>
>     Thank you for the report. It was a bug in our code. I have fixed the
> code in the master and next branch of the PETSc repository. We will be
> making a PETSc release in the next few days that will have the fix.
>
>    Barry
>
> > On Apr 13, 2016, at 9:13 AM, John Mousel <john.mousel at gmail.com> wrote:
> >
> > Barry,
> >
> > I've attached a small example that replicates this behavior.
> >
> > John
> >
> > On Wed, Apr 13, 2016 at 9:25 AM, Barry Smith <bsmith at mcs.anl.gov> wrote:
> >
> >    John,
> >
> >     We'll need the full code to debug this. It doesn't see this should
> happen.
> >
> >    Barry
> >
> > > On Apr 13, 2016, at 7:11 AM, John Mousel <john.mousel at gmail.com>
> wrote:
> > >
> > > I have a colleague who is trying to run some simple test cases. He
> noticed if he provides the solution vector as the exact solution with a
> non-zero guess tagged, that the solution vector is zeroed upon return after
> 0 iterations. The system is just a 5x5 matrix corresponding to a heat
> equation with Dirichlet BCs. I've copied the KSPView below. He's using
> petsc-3.6.3.
> > >
> > > John
> > >
> > > solution before kspsolve:Vec Object: 1 MPI processes
> > >   type: mpi
> > > Process [0]
> > > 300
> > > 300
> > > 300
> > > 300
> > > 300
> > > KSP Object: 1 MPI processes
> > >   type: bcgs
> > >   maximum iterations=100
> > >   tolerances:  relative=1e-15, absolute=1e-50, divergence=10000
> > >   right preconditioning
> > >   using nonzero initial guess
> > >   using UNPRECONDITIONED norm type for convergence test
> > > PC Object: 1 MPI processes
> > >   type: ilu
> > >     ILU: out-of-place factorization
> > >     0 levels of fill
> > >     tolerance for zero pivot 2.22045e-14
> > >     matrix ordering: natural
> > >     factor fill ratio given 1, needed 1
> > >       Factored matrix follows:
> > >         Mat Object:         1 MPI processes
> > >           type: seqaij
> > >           rows=5, cols=5
> > >           package used to perform factorization: petsc
> > >           total: nonzeros=25, allocated nonzeros=25
> > >           total number of mallocs used during MatSetValues calls =0
> > >             using I-node routines: found 1 nodes, limit used is 5
> > >   linear system matrix = precond matrix:
> > >   Mat Object:   1 MPI processes
> > >     type: seqaij
> > >     rows=5, cols=5
> > >     total: nonzeros=25, allocated nonzeros=25
> > >     total number of mallocs used during MatSetValues calls =0
> > >       using I-node routines: found 1 nodes, limit used is 5
> > > solution after kspsolve:Vec Object: 1 MPI processes
> > >   type: mpi
> > > Process [0]
> > > 0
> > > 0
> > > 0
> > > 0
> > > 0
> >
> >
> > <ex1.c>
>
>
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