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

[Barry Smith]

> On Oct 25, 2016, at 12:31 PM, Matthew Knepley <knepley at gmail.com> wrote:
> 
> 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().

   I agree with Matt on this.

> 
>   Thanks,
> 
>      Matt
>  
> > We tried a similar approach to get MFEM objects to PETSc and the real
> > problem is that all other convenient functions like creating
> > gridfunctions and projections, you have to convert them every time
> > which is basically nothing more than a bad workaround.
> 
> So far, my interface covers matrices and Krylov solvers (PCFieldSplit and PCBDDC are explicitly supported).
> 
> Can you tell me how would you like to use these objects with PETSc? What you would like to achieve?
> 
> So far, my work on the PETSc interface to MFEM originated from a wishlist for solvers, but I could expand it.
> 
> 
> > Stefano Zampini
> > replied to the issue on github and was stating that there is some
> > intention to get MFEM working with PETSc but there is no specific
> > timeframe.
> >
> 
> There’s currently an open pull request for PETSc solvers inside the private MFEM repo.
> However, I don’t know when the code, if merged, will be released.
> 
> 
> > Regards
> > Julian Andrej
> >
> > On Tue, Oct 25, 2016 at 6:30 PM, Abdullah Ali Sivas
> > <abdullahasivas at gmail.com> wrote:
> >> I will check that. I am preallocating but it may be that I am not allocating
> >> big enough. I still have to figure out nuance differences between these
> >> formats to solve the bugs. I appreciate your answer and hope Satish knows
> >> it.
> >>
> >> Thank you,
> >> Abdullah Ali Sivas
> >>
> >>
> >> On 2016-10-25 12:15 PM, Matthew Knepley wrote:
> >>
> >> On Tue, Oct 25, 2016 at 10:54 AM, Abdullah Ali Sivas
> >> <abdullahasivas at gmail.com> wrote:
> >>>
> >>> Hello,
> >>>
> >>> I want to use PETSc with mfem and I know that mfem people will figure out
> >>> a way to do it in few months. But for now as a temporary solution I just
> >>> thought of converting hypre PARCSR matrices (that is what mfem uses as
> >>> linear solver package) into PETSc MPIAIJ matrices and I have a semi-working
> >>> code with some bugs. Also my code is dauntingly slow and seems like not
> >>> scaling. I have used MatHYPRE_IJMatrixCopy from myhp.c of PETSc and
> >>> hypre_ParCSRMatrixPrintIJ from par_csr_matrix.c of hypre as starting points.
> >>> Before starting I checked whether there was anything done similar to this, I
> >>> could not find anything.
> >>>
> >>> My question is, are you aware of such a conversion code (i.e. something
> >>> like hypre_ParCSRtoPETScMPIAIJ( hypre_ParCSRMatrix *matrix, Mat *A)?
> >>
> >> No, but maybe Satish knows. Slow running times most likely come from lack of
> >> preallocation for the target matrix.
> >>
> >>  Thanks,
> >>
> >>     Matt
> >>>
> >>> Thanks in advance,
> >>> Abdullah Ali Sivas
> >>
> >>
> >>
> >>
> >> --
> >> 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
> >>
> >>
> 
> 
> 
> 
> -- 
> 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