Hi Matt,
I just got your answer. Thanks for confirming my diagnostic.
I will look at the code and do my best : )
I'll keep you posted on my progresses and issues.

Best,
Luc

On 03/02/2014 02:33 PM, Matthew Knepley wrote:
On Fri, Feb 28, 2014 at 8:18 PM, Luc Berger-Vergiat <[email protected] <mailto:[email protected]>> wrote:

    Hi all,
    sorry for the cryptic title but this is a little complex.
    Here is what I am doing:
    I created a DMShell that gets four fields passed from a PetscSection.
    Now I am doing this because I want to apply a schur complement to
    my problem.
    In order to do so I pass the following arguments to my code:

    -ksp_type gmres
    -pc_type fieldsplit
    -pc_fieldsplit_type schur
    -pc_fieldsplit_schur_factorization_type full
    -pc_fieldsplit_0_fields 2,3                    <--- This define
    A00 for my schur
    -pc_fieldsplit_1_fields 0,1

    Up to here everything works fine and as expected (I actually do a
    -ksp_view to make sure that everything makes sense).
    Now things get tricky, I would like to compute A00^-1 using
    another schur decomposition so here are the commands I issue:

    -fieldsplit_0_ksp_type preonly
    -fieldsplit_0_pc_type fieldsplit
        -fieldsplit_0_pc_fieldsplit_type schur
    -fieldsplit_0_pc_fieldsplit_schur_factorization_type full
    -fieldsplit_0_pc_fieldsplit_0_fields 2
    -fieldsplit_0_pc_fieldsplit_1_fields 3

    I am almost sure that the 4 first commands are correct, I am not
    however sure that the last two are understood by PETSc.
    Actually I am worried that the DMShell that I created for the
    first level schur is not passed on the second level schur.
    Here is the error message I get when I run my code:


Sorry, I am really bogged down at the moment. Can you try this:

1) You do not need to specify 2,3 for the inner fields since it will use them automatically

2) Can you try changing src/dm/impls/shell/dmshell.c:664 to include DMSetUp(*subdm); ?

  Thanks,

      Matt

    [0]PETSC ERROR: --------------------- Error Message
    ------------------------------------
    [0]PETSC ERROR: Object is in wrong state!
    [0]PETSC ERROR: Decomposition defined only after DMSetUp!
    [0]PETSC ERROR:
    ------------------------------------------------------------------------
    [0]PETSC ERROR: Petsc Development GIT revision:
    v3.4.3-4597-g3edecfd  GIT Date: 2014-02-20 20:43:18 -0600
    [0]PETSC ERROR: See docs/changes/index.html for recent updates.
    [0]PETSC ERROR: See docs/faq.html for hints about trouble shooting.
    [0]PETSC ERROR: See docs/index.html for manual pages.
    [0]PETSC ERROR:
    ------------------------------------------------------------------------
    [0]PETSC ERROR:
    /home/luc/research/feap_repo/ShearBands/parfeap-petsc34/feap on a
    arch-linux2-c-opt named euler by luc Fri Feb 28 20:07:18 2014
    [0]PETSC ERROR: Libraries linked from
    /home/luc/research/petsc/arch-linux2-c-opt/lib
    [0]PETSC ERROR: Configure run at Fri Feb 21 17:31:31 2014
    [0]PETSC ERROR: Configure options --download-cmake
    --download-hypre --download-metis --download-mpich
    --download-parmetis --with-debugging=0 --with-share-libraries=0
    [0]PETSC ERROR:
    ------------------------------------------------------------------------
    [0]PETSC ERROR: DMCreateFieldDecomposition() line 1262 in
    /home/luc/research/petsc/src/dm/interface/dm.c
    [0]PETSC ERROR: PCFieldSplitSetDefaults() line 336 in
    /home/luc/research/petsc/src/ksp/pc/impls/fieldsplit/fieldsplit.c
    [0]PETSC ERROR: PCSetUp_FieldSplit() line 485 in
    /home/luc/research/petsc/src/ksp/pc/impls/fieldsplit/fieldsplit.c
    [0]PETSC ERROR: PCSetUp() line 888 in
    /home/luc/research/petsc/src/ksp/pc/interface/precon.c
    [0]PETSC ERROR: KSPSetUp() line 278 in
    /home/luc/research/petsc/src/ksp/ksp/interface/itfunc.c
    [0]PETSC ERROR: KSPSolve() line 390 in
    /home/luc/research/petsc/src/ksp/ksp/interface/itfunc.c
    [0]PETSC ERROR: PCApply_FieldSplit_Schur() line 859 in
    /home/luc/research/petsc/src/ksp/pc/impls/fieldsplit/fieldsplit.c
    [0]PETSC ERROR: PCApply() line 440 in
    /home/luc/research/petsc/src/ksp/pc/interface/precon.c
    [0]PETSC ERROR: KSP_PCApply() line 227 in
    /home/luc/research/petsc/include/petsc-private/kspimpl.h
    [0]PETSC ERROR: KSPInitialResidual() line 64 in
    /home/luc/research/petsc/src/ksp/ksp/interface/itres.c
    [0]PETSC ERROR: KSPSolve_GMRES() line 234 in
    /home/luc/research/petsc/src/ksp/ksp/impls/gmres/gmres.c
    [0]PETSC ERROR: KSPSolve() line 432 in
    /home/luc/research/petsc/src/ksp/ksp/interface/itfunc.c

    Let me know if I'm doing something wrong or misunderstood something.

    Best,
    Luc




--
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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