[petsc-users] Troubles updating my code from PETSc-3.4 to 3.5 Using MUMPS for KSPSolve()

[Matthew Knepley]

On Thu, Dec 11, 2014 at 4:38 AM, Marc MEDALE <marc.medale at univ-amu.fr>
wrote:

> Dear PETSC Users,
>
> I have just updated to PETSc-3.5 my research code that uses PETSc for a
> while but I'm facing an astonishing difference between PETSc-3.4 to 3.5
> versions when solving a very ill conditioned algebraic system with MUMPS
> (4.10.0 in both cases).
>
> The only differences that arise in my fortran source code are the
> following:
> Loma1-medale% diff ../version_3.5/solvEFL_MAN_SBIF.F
> ../version_3.4/solvEFL_MAN_SBIF.F
> 336,337d335
> <       CALL MatSetOption(MATGLOB,MAT_KEEP_NONZERO_PATTERN,
> <      &       PETSC_TRUE,IER)
> 749,750c747,748
> <       CALL KSPSetTolerances(KSP1,TOL,PETSC_DEFAULT_REAL,
> <      &     PETSC_DEFAULT_REAL,PETSC_DEFAULT_INTEGER,IER)
> ---
> >       CALL KSPSetTolerances(KSP1,TOL,PETSC_DEFAULT_DOUBLE_PRECISION,
> >      &     PETSC_DEFAULT_DOUBLE_PRECISION,PETSC_DEFAULT_INTEGER,IER)
> 909c907,908
> <           CALL KSPSetOperators(KSP1,MATGLOB,MATGLOB,IER)
> ---
> >           CALL KSPSetOperators(KSP1,MATGLOB,MATGLOB,
> >      &                         SAME_NONZERO_PATTERN,IER)
>
> When I run the corresponding program versions on 128 cores of our cluster
> with the same input data and the following command line arguments:
> -ksp_type preonly -pc_type lu -pc_factor_mat_solver_package mumps
> -mat_mumps_icntl_8 0
>
> I get the following outputs:
> a)  with PETSc-3.4p4:
>         L2 norm of solution vector: 7.39640E-02,
>
> b)  with PETSc-3.5p1:
>         L2 norm of solution vector: 1.61325E-02
>
> Do I have change something else in updating my code based on KSP from
> PETSc-3.4 to 3.5 versions?
> Do any default values in the PETSc-MUMPS interface have been changed from
> PETSc-3.4 to 3.5?
> Any hints or suggestions are welcome to help me to recover the right
> results (obtained with PETSc-3.4).
>

Send the output from -ksp_monitor -ksp_view for both runs. I am guessing
that a MUMPS default changed between versions.

  Thanks,

    Matt


> Thank you very much.
>
> Marc MEDALE.




-- 
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
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.mcs.anl.gov/pipermail/petsc-users/attachments/20141211/657b9f4b/attachment.html>