[petsc-users] PCFieldSplitSetSchurPre in fortran

[Matthew Knepley]

On Fri, Aug 29, 2014 at 8:55 AM, Klaij, Christiaan <C.Klaij at marin.nl> wrote:

> I'm trying PCFieldSplitSetSchurPre with
> PC_FIELDSPLIT_SCHUR_PRE_SELFP in petsc-3.5.1 using fortran.
>
> The first problem is that PC_FIELDSPLIT_SCHUR_PRE_SELFP seems to
> be missing in fortran, I get the compile error:
>
> This name does not have a type, and must have an explicit type.
>  [PC_FIELDSPLIT_SCHUR_PRE_SELFP]
>
> while compilation works fine with _A11, _SELF and _USER.
>

Mark Adams has just fixed this.


> The second problem is that the call doesn't seem to have any
> effect. For example, I have
>
> CALL PCFieldSplitSetSchurPre(pc,PC_FIELDSPLIT_SCHUR_PRE_USER,aa,ierr)
> CALL PCFieldSplitSetSchurFactType(pc,PC_FIELDSPLIT_SCHUR_FACT_LOWER,ierr)
>
> This compiles and runs, but ksp_view tells me
>
> PC Object:(sys_) 3 MPI processes
>   type: fieldsplit
>     FieldSplit with Schur preconditioner, factorization LOWER
>     Preconditioner for the Schur complement formed from A11
>
> So changing the factorization from the default FULL to LOWER did
> work, but changing the preconditioner from A11 to USER didn't.
>
> I've also tried to run directly from the command line using
>
> -sys_pc_fieldsplit_schur_precondition user -sys_ksp_view
>
> This works in the sense that I don't get the "WARNING! There are
> options you set that were not used!" message, but still ksp_view
> reports A11 instead of user provided matrix.
>

Can you send a small test code, since I use this everyday here and it works.

  Thanks,

     Matt


> Chris
>
>
> dr. ir. Christiaan Klaij
> CFD Researcher
> Research & Development
> E mailto:C.Klaij at marin.nl
> T +31 317 49 33 44
>
>
> MARIN
> 2, Haagsteeg, P.O. Box 28, 6700 AA Wageningen, The Netherlands
> T +31 317 49 39 11, F +31 317 49 32 45, I www.marin.nl
>
>


-- 
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
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