[petsc-users] Is it possible to use -snes_ksp_ew in the framework of KSP?

[Matthew Knepley]

On Fri, Mar 7, 2014 at 1:21 PM, Song Gao <song.gao2 at mail.mcgill.ca> wrote:

> Hello,
>
> We are working on a legacy codes which solves the NS equations. The codes
> take control of newton iterations itself and use KSP to solve the linear
> system.
>
> We modified the codes, used SNES to control the newton iteration and
> changed the code to matrix free fashion. But the legacy codes did a lot of
> other things between two newton iterations (such as output solution, update
> variables....). I know we could use linesearchpostcheck but it is
> difficulty to do that correctly. Therefore, we decide to go back to the KSP
> framework but still use matrix free.
>

What makes it difficult?

  Thanks,

     Matt


> When using SNES, we always use the runtime option -snes_ksp_ew, we observe
> that for some test cases, the residual stalls without -snes_ksp_ew, but
> converges with-snes_ksp_ew. So I'm thinking if it is possible to
> use -snes_ksp_ew in KSP? Thanks in advance.
>
>
>


-- 
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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