[petsc-users] Use previous solution when encountering "DIVERGED_LINE_SEARCH"

[Matthew Knepley]

On Wed, Nov 30, 2016 at 8:27 PM, Justin Chang <jychang48 at gmail.com> wrote:

> Hi all,
>
> I am running some transient simulations using SNESVINEWTONRSLS. At
> certain timesteps, I get a "DIVERGED_LINE_SEARCH" which essentially
> "resets" my solution to zero and messes everything up. I notice that this
> happens when the SNES Function norm no longer decreases, and if I were to
> manually terminate the solver right before the final iteration I get the
> answer I want.
>

Yes, its possible, however isn't that a dangerous way to terminate?
Couldn't you terminate on stagnation?

  Thanks,

     Matt


> Is there a way to "detect" this error and use the solution from the
> previous non-failing iteration? Setting a fixed maximum iteration doesn't
> seem reasonble because every time level will require different numbers of
> iterations to converge.
>
> Thanks,
> Justin
>



-- 
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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