[petsc-dev] How to get the subsnes from a nonlinear problem

[Matthew Knepley]

On Sun, Feb 18, 2018 at 1:59 AM, Lulu Liu <lulu.liu at kaust.edu.sa> wrote:

> Hi,
>
> I am trying to use nonlinear elimination (NE) to solve a nonlinear
> problem, and I have to solve  a subproblem.  How to get the subsnes from
> the original global nonlinear problem? Is there any easy way to do it?
>

Are you doing NE using SNESCOMPOSITE or a nonlinear preconditioner. If the
NPC, can you use


http://www.mcs.anl.gov/petsc/petsc-current/docs/manualpages/SNES/SNESGetNPC.html

  Thanks,

     Matt


> For example, the global problem is defined on 40x40 mesh, and the local
> problem (the size is 5x5) is defined in the center of domain [0,1]x[0,1].
>
> Thanks!
>
>
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