[petsc-users] snes_type aspin error

[Matthew Knepley]

On Thu, Jun 23, 2016 at 2:43 PM, Barry Smith <bsmith at mcs.anl.gov> wrote:

>
> > On Jun 23, 2016, at 1:36 PM, Xiangdong <epscodes at gmail.com> wrote:
> >
> > Hi Barry and Matt,
> >
> > The behavior I reported before can be reproduced with snes example ex18.
> >
> http://www.mcs.anl.gov/petsc/petsc-current/src/snes/examples/tutorials/ex18.c.html
> >
> > ./ex18 -sens_type aspin -snes_fd_color is okay;
> >
> > ./ex18 -snes_type aspin crashes.
> >
> > So there is something messed up in the function  FormJacobian(SNES
> snes,Vec X,Mat jac,Mat jacpre,void *ptr).
> >
> > If the analytical Jacobian is calculated and put into the matrix jac
> (like ex18.c), the program crash with the aspin option. However, if the
> same analytical Jacobian is put into jacpre (like ex20.c), it works fine
> with the aspin option.
> >
> > In general, for the analytical Jacobian, should I put it into jac or
> jacpre in the FormJaciban() function?
>
>    Thanks for figuring this out; it is exactly the problem. When providing
> explicit Jacobian entries; either analytic or some approximation they
> should always be set in the second Mat argument the jacpre matrix, not in
> the first matrix argument. I have fixed ex18.c in the maint branch to use
> the second matrix argument and now the aspin type runs fine.
>
>   The reason they should be set in the second argument is that in some
> circumstances including -snes_mf_operator and with aspin PC internally, in
> the PETSc solvers, we change the first mat argument to some other form that
> one cannot set values directly into such as a matrix-free operator or a
> shell operator.
>
>    The reason ./ex18 -sens_type aspin -snes_fd_color is okay is because
> PETSc manages setting the matrix entries when doing the Jacobian with
> coloring and skips the user provided (in this case wrong) FormJacobian()
> function.


Should we have an error check for J != P and J a Mat?

   Matt


>
>   Barry
>
> >
> > Thanks.
> >
> > Best,
> > Xiangdong
> >
> >
> >
> >
> > On Mon, Jun 20, 2016 at 9:51 PM, Barry Smith <bsmith at mcs.anl.gov> wrote:
> >
> >   Could you reproduce the error with a PETSc example or send us the
> code? If we can run a code that generates an error then we can debug it and
> maybe fix it. If we can't run something with the same error it is hard for
> us to fix it. We'd just be making wild guesses.
> >
> >   Barry
> >
> > > On Jun 20, 2016, at 8:06 PM, Xiangdong <epscodes at gmail.com> wrote:
> > >
> > >
> > >
> > > On Mon, Jun 20, 2016 at 1:02 PM, Barry Smith <bsmith at mcs.anl.gov>
> wrote:
> > >
> > >    Are you providing a shell matrix to the solver?
> > >
> > > No. The matrix (global Jacobian) is setup by MatSetValuesStencil. It
> works for the standard newtonls as well as nasm preconditioner. I think the
> aspin will assemble the new Jacobian for me based on the information of old
> Jacobian.
> > >
> > > Do I need to provide something special to use the aspin?
> > >
> > > Thanks.
> > >
> > > Best,
> > > Xiangdong
> > >
> > >  Barry
> > >
> > > > On Jun 20, 2016, at 11:32 AM, Xiangdong <epscodes at gmail.com> wrote:
> > > >
> > > > Hello everyone,
> > > >
> > > > I am trying different snes_type in petsc. The newtonls and nasm all
> works well. However, when I switched to aspin, I got the error like "No
> support for this operation for this object type" "Mat type shell". I am
> using the dmda 3d in petsc 3.6.3. The full error messages are below.
> > > >
> > > > Any hint for me to fix this? Thanks.
> > > >
> > > > Best,
> > > > Xiangdong
> > > >
> > > > [0]PETSC ERROR: --------------------- Error Message
> --------------------------------------------------------------
> > > > [0]PETSC ERROR: No support for this operation for this object type
> > > > [0]PETSC ERROR: Mat type shell
> > > > [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, unknown
> > > > [0]PETSC ERROR: #1 MatZeroEntries() line 5404 in
> /home/shared/MyLocal_stor/petsc/petsc-dev/src/mat/interface/matrix.c
> > > > [0]PETSC ERROR: #2 FormJacobianLocal() line 37 in
> /home/MyCodes/epscprplus/Jacobian.c
> > > > [0]PETSC ERROR: #3 SNESComputeJacobian_DMDA() line 175 in
> /home/shared/MyLocal_stor/petsc/petsc-dev/src/snes/utils/dmdasnes.c
> > > > [0]PETSC ERROR: #4 SNESComputeJacobian() line 2232 in
> /home/shared/MyLocal_stor/petsc/petsc-dev/src/snes/interface/snes.c
> > > > [0]PETSC ERROR: #5 SNESNASMComputeFinalJacobian_Private() line 770
> in /home/shared/MyLocal_stor/petsc/petsc-dev/src/snes/impls/nasm/nasm.c
> > > > [0]PETSC ERROR: #6 SNESSolve_NASM() line 888 in
> /home/shared/MyLocal_stor/petsc/petsc-dev/src/snes/impls/nasm/nasm.c
> > > > [0]PETSC ERROR: #7 SNESSolve() line 3906 in
> /home/shared/MyLocal_stor/petsc/petsc-dev/src/snes/interface/snes.c
> > > > [0]PETSC ERROR: #8 SNESApplyNPC() line 48 in
> /home/shared/MyLocal_stor/petsc/petsc-dev/src/snes/interface/snespc.c
> > > > [0]PETSC ERROR: #9 SNESSolve_NEWTONLS() line 173 in
> /home/shared/MyLocal_stor/petsc/petsc-dev/src/snes/impls/ls/ls.c
> > > > [0]PETSC ERROR: #10 SNESSolve() line 3906 in
> /home/shared/MyLocal_stor/petsc/petsc-dev/src/snes/interface/snes.c
> > > > [0]PETSC ERROR: #11 main() line 794 in
> /home/MyCodes/epscprplus/twophaseow.c
> > > >
> > >
> > >
> >
> >
>
>


-- 
What most experimenters take for granted before they begin their
experiments is infinitely more interesting than any results to which their
experiments lead.
-- Norbert Wiener
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