[petsc-users] fieldsplit: Unhandled case, must have at least two fields, not 1!

[Nico Schlömer]

For the record, the problem I had was caused by the fact that I
 * first created the solver,
 * then set
    PetscOptionsSetValue('pc_type', 'fieldsplit')

Reverting the order of the two calls gives the expected results.

Cheers,
Nico


e0319bd95940fc10e07f4fba29a91a8713afd825

On Mon, Dec 2, 2013 at 5:03 PM, Jed Brown <jedbrown at mcs.anl.gov> wrote:
> Mark Adams <mfadams at lbl.gov> writes:
>> My point was that this user got this message and so I suggesting a possible
>> problem: giving fieldsplit parameters to a single field matrix/solver.
>
> Okay, I interpreted your original statement as being that this error
> message has something to do with using monolithic matrix formats (such
> as AIJ, versus Nest), which it does not, and that you thought the error
> message was problematic behavior.
>
> Your very complicated test case (hundreds of processes, with multiple
> solves, some intending to use fieldsplit, Schur, MatNest, tinkering with
> the options database, huge differences between the two options files)
> can be reduced to src/ksp/ksp/examples/tutorials/ex2.c.
>
> $ ./ex2 -pc_type fieldsplit
> [0]PETSC ERROR: --------------------- Error Message ------------------------------------
> [0]PETSC ERROR: Petsc has generated inconsistent data!
> [0]PETSC ERROR: Unhandled case, must have at least two fields, not 1!
> [0]PETSC ERROR: ------------------------------------------------------------------------
> [0]PETSC ERROR: Petsc Development GIT revision: ad348534bf2da17dbc29a6a7895b244965ac0e39  GIT Date: 2013-11-13 12:43:46 -0700
> [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: ./ex2 on a mpich named batura by jed Mon Dec  2 09:55:54 2013
> [0]PETSC ERROR: Libraries linked from /home/jed/petsc/mpich/lib
> [0]PETSC ERROR: Configure run at Wed Nov 13 13:33:49 2013
> [0]PETSC ERROR: Configure options --download-blacs --download-chaco --download-ctetgen --download-elemental --download-generator --download-hypre --download-metis --download-ml --download-mumps --download-parmetis --download-scalapack --download-spai --download-spooles --download-sundials --download-superlu --download-superlu_dist --download-triangle --with-blas-lapack=/usr --with-c2html --with-cholmod-dir=/usr --with-cxx-dialect=C++11 --with-exodusii-dir=/usr --with-hdf5-dir=/opt/mpich --with-lgrind --with-mpi-dir=/home/jed/usr/ccache/mpich/ --with-netcdf-dir=/usr --with-openmp --with-pcbddc --with-pthread --with-shared-libraries --with-single-library=0 --with-sowing --with-threadcomm --with-umfpack-dir=/usr --with-x -PETSC_ARCH=mpich COPTFLAGS="-Og -g" CXXOPTFLAGS="-Og -g" FOPTFLAGS="-Og -g"
> [0]PETSC ERROR: ------------------------------------------------------------------------
> [0]PETSC ERROR: PCFieldSplitSetDefaults() line 441 in src/ksp/pc/impls/fieldsplit/fieldsplit.c
> [0]PETSC ERROR: PCSetUp_FieldSplit() line 459 in src/ksp/pc/impls/fieldsplit/fieldsplit.c
> [0]PETSC ERROR: PCSetUp() line 888 in src/ksp/pc/interface/precon.c
> [0]PETSC ERROR: KSPSetUp() line 278 in src/ksp/ksp/interface/itfunc.c
> [0]PETSC ERROR: KSPSolve() line 399 in src/ksp/ksp/interface/itfunc.c
> [0]PETSC ERROR: main() line 198 in /home/jed/petsc/src/ksp/ksp/examples/tutorials/ex2.c
> application called MPI_Abort(MPI_COMM_WORLD, 77) - process 0