[petsc-users] Error message for DMShell using MG preconditioner to solve S

[Matthew Knepley]

On Tue, May 20, 2014 at 4:33 PM, Luc Berger-Vergiat <lb2653 at columbia.edu>wrote:

>  Hi all,
> I am running an FEM simulation that uses Petsc as a linear solver.
> I am setting up ISs and pass them to a DMShell in order to use the
> FieldSplit capabilities of Petsc.
>
> When I pass the following options to Petsc:
>
> " -ksp_type gmres -pc_type fieldsplit -pc_fieldsplit_type schur
> -pc_fieldsplit_schur_factorization_type full
> -pc_fieldsplit_schur_precondition selfp -pc_fieldsplit_0_fields 1,2
> -pc_fieldsplit_1_fields 0 -fieldsplit_0_ksp_type preonly
> -fieldsplit_0_pc_type ilu -fieldsplit_Field_0_ksp_type gmres
> -fieldsplit_Field_0_pc_type mg -malloc_log mlog -log_summary time.log"
>
> I get an error message:
>
> [0]PETSC ERROR: --------------------- Error Message
> --------------------------------------------------------------
> [0]PETSC ERROR:
> [0]PETSC ERROR: Must call DMShellSetGlobalVector() or
> DMShellSetCreateGlobalVector()
> [0]PETSC ERROR: See
> http://http://www.mcs.anl.gov/petsc/documentation/faq.html for trouble
> shooting.
> [0]PETSC ERROR: Petsc Development GIT revision: v3.4.4-5071-g1163a46  GIT
> Date: 2014-03-26 22:20:51 -0500
> [0]PETSC ERROR: /home/luc/research/feap_repo/ShearBands/parfeap-dev/feap
> on a arch-linux2-c-opt named euler by luc Tue May 20 11:31:11 2014
> [0]PETSC ERROR: Configure options --download-cmake --download-hypre
> --download-metis --download-mpich --download-parmetis --with-debugging=no
> --with-share-libraries=no
> [0]PETSC ERROR: #1 DMCreateGlobalVector_Shell() line 245 in
> /home/luc/research/petsc/src/dm/impls/shell/dmshell.c
> [0]PETSC ERROR: #2 DMCreateGlobalVector() line 669 in
> /home/luc/research/petsc/src/dm/interface/dm.c
> [0]PETSC ERROR: #3 DMGetGlobalVector() line 154 in
> /home/luc/research/petsc/src/dm/interface/dmget.c
>

Always always always give the entire error message.

  Matt


> I am not really sure why this happens but it only happens when
> -fieldsplit_Field_0_pc_type mg, with other preconditioners, I have no
> problems. I attached the ksp_view in case that's any use.
>
> --
> 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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