[petsc-users] Using PETSc solvers and preconditioners with mfem

[Abdullah Ali Sivas]

@Stefano Zampini:

I am planning to do two things. One is to directly use Krylov solvers 
and preconditioners available to PETSc to try out some stuff and make 
some matrix manipulations like symmetric diagonal scaling or getting a 
submatrix. If that works I will implement few things (preconditioners or 
other krylov solvers) using PETSc and try them out. So what you did is 
like a blessing for me (basically because I was working on the very same 
thing for days now) and thank you for that.


@Mark and Jed

These are great ideas and I believe a lot of users like me will be 
grateful if these are available.

On 2016-10-25 01:50 PM, Jed Brown wrote:
> Matthew Knepley <knepley at gmail.com> writes:
>
>> On Tue, Oct 25, 2016 at 12:19 PM, Stefano Zampini <stefano.zampini at gmail.com
>>> wrote:
>>> I have a working conversion from HypreParCSR to PETSc MPIAIJ format.
>>> I could add this code to PETSc, maybe in the contrib folder. Barry, what
>>> do you think?
>>>
>> No, no one looks there. Add it to src/mat/utils and make an interface
>> function like MatCreateFromHypreParCSR().
> Note that mhyp.c contains code to convert AIJ matrices to ParCSR.  If we
> were to create a MatHypreParCSR implementation, we could use those
> functions for MatConvert_{Seq,MPI}AIJ_HypreParCSR and use your function
> for the reverse.  That would be consistent with how external matrix
> formats are normally represented and may enable some new capability to
> mix PETSc and Hypre components in the future.  Here, I'm envisioning
>
>    PetscErrorCode MatCreateHypreParCSR(hyper_ParCSRMatrix *A,Mat *B);
>
> This way, if a user chooses -pc_type hypre, there would be no copies for
> going through PETSc.  Similarly, if we implement
> MatSetValues_HypreParCSR, a pure PETSc application could use Hypre
> preconditioners with no copies.