[petsc-users] MUMPS icntl for petsc4py

[Quentin Chevalier]

Makes sense. Thanks again !

On Mon, 23 Jan 2023, 16:28 Jose E. Roman, <jroman at dsic.upv.es> wrote:

> Here is the explanation. With shift-and-invert, two main things must be
> done at STSetUp: 1) build the matrix A-sigma*B, (2) factorize it. Normally
> this is done at the beginning of EPSSolve. Before that you can set PC
> options, but the problem is that MUMPS options belong to Mat, not PC, so
> step 1) must be done beforehand. But you cannot call PCSetUp because you
> have not yet configured MUMPS options. Around version 3.12 we split the
> implementation of STSetUp so that 1) and 2) can be done separately.
> STGetOperator is what triggers 1).
>
> Jose
>
>
> > El 23 ene 2023, a las 13:13, Quentin Chevalier <
> quentin.chevalier at polytechnique.edu> escribió:
> >
> > Many thanks Jose, it works beautifully !
> >
> > I'm at a loss as to why, but thanks for the quick fix !
> >
> > Quentin
> >
> >
> >
> > Quentin CHEVALIER – IA parcours recherche
> >
> > LadHyX - Ecole polytechnique
> >
> > __________
> >
> >
> >
> > On Sun, 22 Jan 2023 at 10:58, Jose E. Roman <jroman at dsic.upv.es> wrote:
> >>
> >> You have to call ST.getOperator() as is done in this C example:
> >>
> https://slepc.upv.es/documentation/current/src/eps/tutorials/ex43.c.html
> >>
> >> Jose
> >>
> >>
> >>> El 22 ene 2023, a las 10:40, Quentin Chevalier <
> quentin.chevalier at polytechnique.edu> escribió:
> >>>
> >>> Hello PETSc users,
> >>>
> >>> I'm getting an INFOG(1)=-9 and INFO(2)=27 error on an eigenvalue code
> based on dolfinx run in a docker container. Based on
> https://mumps-solver.org/doc/userguide_5.5.1.pdf, I figured the fix would
> be to increase ICNTL(14).
> >>>
> >>> I'm coding in python through the petsc4py/slepc4py wrapper. I found a
> Mat.setMumpsIcntl method but I can't seem to place it properly and always
> obtain another error : "Operation done in wrong order and the like".
> >>>
> >>> Here's the code snippet that is failing :
> >>> # Solver
> >>> EPS = SLEPc.EPS().create(COMM_WORLD)
> >>> EPS.setOperators(-A,M) # Solve Ax=sigma*Mx
> >>> EPS.setProblemType(SLEPc.EPS.ProblemType.PGNHEP) # Specify that A is
> not hermitian, but M is semi-definite
> >>> EPS.setWhichEigenpairs(EPS.Which.TARGET_MAGNITUDE) # Find eigenvalues
> close to sigma
> >>> EPS.setTarget(sigma)
> >>> EPS.setDimensions(2,10) # Find k eigenvalues only with max number of
> Lanczos vectors
> >>> EPS.setTolerances(1e-9,100) # Set absolute tolerance and number of
> iterations
> >>> # Spectral transform
> >>> ST = EPS.getST(); ST.setType('sinvert')
> >>> # Krylov subspace
> >>> KSP = ST.getKSP()
> >>> KSP.setTolerances(rtol=1e-6, atol=1e-9, max_it=100)
> >>> # Krylov subspace
> >>> KSP.setType('preonly')
> >>> # Preconditioner
> >>> PC = KSP.getPC(); PC.setType('lu')
> >>> PC.setFactorSolverType('mumps')
> >>> KSP.setFromOptions()
> >>> EPS.setFromOptions()
> >>> PC.getFactorMatrix().setMumpsIcntl(14,50)
> >>> print(f"Solver launch for sig={sigma:.1f}...",flush=True)
> >>> EPS.solve()
> >>> n=EPS.getConverged()
> >>>
> >>> For context, matrix A is complex, size 500k x 500k but AIJ sparse, and
> I'm running this code on 36 nodes.
> >>>
> >>> I'd appreciate any insight on how to fix this issue, it's not clear to
> me what the order of operations should be. Funnily enough, it's very
> shift-dependent.
> >>>
> >>> Cheers,
> >>>
> >>> Quentin
> >>
>
>
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