[petsc-users] Fieldsplit schur applied on A00 of a fieldsplit schur

[Luc]

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 
> <luc.berger.vergiat at gmail.com <mailto:luc.berger.vergiat at gmail.com>> 
> 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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