[petsc-users] Petsc+Chombo example

[Mani Chandra]

Thanks for the information. I'm familiar with SNES+DMDA, just not sure it
would work with Chombo. But I'll give it a shot.

Cheers,
Mani

On Wed, Aug 12, 2015 at 5:56 PM, Mark Adams <mfadams at lbl.gov> wrote:

>
>
> On Wed, Aug 12, 2015 at 2:29 PM, Mani Chandra <mc0710 at gmail.com> wrote:
>
>> Hi,
>>
>>
>>> Chombo (me) creates an MPIAIJ matrix.  So automatic Jacobian assembly
>>> should work.
>>>
>>> I have put a SNES in a Chombo code, but did not use automatic Jacobian
>>> assembly.
>>>
>>
>> Do you have an example?
>>
>
> If you want to make a SNES solver then you need an "apply" call back
> function and a way to map Chombo vectors with PETSc vectors.
>
> Chombo has a level solver (classes derived from PetscSolver) and an AMR
> composite matrix constructor class (classes derived from PetscCompGrid) in
> lib/src/AMRElliptic.  These two class each create these maps, providing
> methods to "putChomboInPetsc", and so forth.
>  lib/src/AMRElliptic/PetscSolverI.H has an apply_mfree() method that is a
> callback function that you give to PETSc to apply an operator.  There are
> examples in Chombo on how to use/construct these two classes, or two
> installations of them.  Each of these classes has a Poisson and a 2D
> Viscous Tensor instantiation.
>
> You probably want to look at PETSc SNES examples if you are not familiar
> with SNES to get an idea of what you need to provide.  Then, look at the
> appropriate Chombo class as a place start.  I am guessing that you will
> want to write your own solver and just use these classes to get these
> mapping methods.  Wrapping a Chombo operator (apply) and solver in a SNES
> is not hard and PetscSolverI.H has examples.
>
> These codes only have one user each (and they are both ANAG staff
> members), so they are pretty immature codes.
>
> Mark
>
>
>> Thanks,
>> Mani
>>
>
>
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