[petsc-users] DIVERGED_LINEAR_SOLVE in SNES

[Li Luo]

Thank you for the suggestions, I'll try it.

Best,
Li

On Fri, Sep 27, 2019 at 5:27 AM Smith, Barry F. <bsmith at mcs.anl.gov> wrote:

>
>   Li,
>
>    It is possible, but as Hong said probably never appropriate. Especially
> if KSP has iterated for 10,000 iterations. If you want SNES to "try" the
> direction given by a failed solve you should use a much smaller maximum
> number of iterations for KSP.
>
>    Anways, to do what you desire
>
> #include <petsc/private/kspimpl.h>
>
> call KSPSetPostSolve() and in your post solve() function simply do
> ksp->reason = KSP_CONVERGED_ITS.
>
>  Barry
>
>
>
>
> > On Sep 26, 2019, at 10:58 AM, Zhang, Hong via petsc-users <
> petsc-users at mcs.anl.gov> wrote:
> >
> > Li :
> > You can use '-ksp_max_it 20000' to change maximum iteration count.
> However, it does not make sense to continue after it fails at 10000
> iterations. You should figure out why linear solver diverges. Run your code
> with '-ksp_monitor' or '-ksp_monitor_true_residual'.
> > Hong
> >
> > Dear developer,
> >
> > I am using SNES for solving a nonlinear system.  For some cases, SNES
> diverged -3 with "DIVERGED_LINEAR_SOLVE" when the linear solver reached its
> maximum iteration count (i.e -ksp_max_it 10000).
> > Is that possible to let SNES continue even though the linear solver
> reaches the maximum number of iterations? Just take the result at 10000 for
> the Jacobian solution and then update the Newton step?
> >
> > Best,
> > Li
> >
> >
> >
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>

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Postdoctoral Fellow
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King Abdullah University of Science & Technology
https://sites.google.com/site/rolyliluo/

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