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

[Justin Chang]

By manually terminating I meant setting -snes_max_it to 5 if I know
DIVERGED_LINE_SEARCH
occurs after 6 iterations. In a transient simulation I cannot do this

On Wed, Nov 30, 2016 at 8:35 PM, Matthew Knepley <knepley at gmail.com> wrote:

> 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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