[petsc-users] Convergence trouble with SNES and CG

[David Knezevic]

On Mon, Feb 22, 2016 at 7:10 PM, Matthew Knepley <knepley at gmail.com> wrote:

> On Mon, Feb 22, 2016 at 6:02 PM, David Knezevic <
> david.knezevic at akselos.com> wrote:
>
>> On Mon, Feb 22, 2016 at 6:57 PM, Barry Smith <bsmith at mcs.anl.gov> wrote:
>>
>>>
>>>   Add -ksp_converged_reason
>>>
>>
>>
>> That gives "DIVERGED_INDEFINITE_PC". The full output is below:
>>
>
> Just for testing, replace CG with GMRES.
>

With GMRES the first four nonlinear iterations behave much that same as
before, converging at KSP iteration 150 or so.

On the 5th nonlinear iteration, GMRES doesn't give a KSP convergence
failure, but the convergence seems to stagnate. It's currently at KSP
iteration 2000, and tolerance of 6e-3 (and still running).

David
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.mcs.anl.gov/pipermail/petsc-users/attachments/20160222/c1bb5268/attachment.html>