[petsc-users] A number of questions about DMDA with SNES and Quasi-Newton methods

[Jed Brown]

Always always always send the whole error message.

"zakaryah ." <zakaryah at gmail.com> writes:

> I tried -snes_compare_explicit, and got the following error:
>
> [0]PETSC ERROR: Invalid argument
>
> [0]PETSC ERROR: Matrix not generated from a DMDA
>
> What am I doing wrong?
>
> On Tue, Oct 3, 2017 at 10:08 AM, Jed Brown <jed at jedbrown.org> wrote:
>
>> Barry Smith <bsmith at mcs.anl.gov> writes:
>>
>> >> On Oct 3, 2017, at 5:54 AM, zakaryah . <zakaryah at gmail.com> wrote:
>> >>
>> >> I'm still working on this.  I've made some progress, and it looks like
>> the issue is with the KSP, at least for now.  The Jacobian may be
>> ill-conditioned.  Is it possible to use -snes_test_display during an
>> intermediate step of the analysis?  I would like to inspect the Jacobian
>> after several solves have already completed,
>> >
>> >    No, our currently code for testing Jacobians is poor quality and
>> poorly organized. Needs a major refactoring to do things properly. Sorry
>>
>> You can use -snes_compare_explicit or -snes_compare_coloring to output
>> differences on each Newton step.
>>