[petsc-users] Setting block size for MPI vectors

[Vijay S. Mahadevan]

I am trying to create an MPI vector and then trying to set the block
size after the initial creation. But I receive an error in
PetscLayoutSetBlockSize. Since there is no explicit block size
argument during construction, I call VecSetBlockSize afterwards. The
relevant code and error are below.

Is there an alternate call to set the block size to the vector so that
VecSetValuesBlocked will work correctly ? If there is no current way
to do this, that's fine and I can try to get the local array and set
the values accordingly.

Code:
ierr = VecCreateMPI(PETSC_COMM_WORLD, 10, PETSC_DECIDE, &x);CHKERRQ(ierr);
ierr = VecSetBlockSize(x, 2);CHKERRQ(ierr);
ierr = VecSetFromOptions(x);CHKERRQ(ierr);

Relevant errors:

0]PETSC ERROR: Arguments are incompatible!
[0]PETSC ERROR: Cannot change block size 1 to 2!
[0]PETSC ERROR:
------------------------------------------------------------------------
[0]PETSC ERROR: Petsc Development GIT revision:
0799ffdeffb47ef0458c1305293fae28c4d2cd92  GIT Date: 2013-08-01
06:36:16 +0800
[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: ./ex1 on a arch-darwin-cxx-debug named
anlextwls002-168.wl.anl-external.org by mahadevan Tue Aug 27 16:37:18
2013
[0]PETSC ERROR: Libraries linked from /opt/petsc-dbg/lib
[0]PETSC ERROR: Configure run at Wed Jul 31 18:03:46 2013
[0]PETSC ERROR: Configure options --prefix=/opt/petsc-dbg
PETSC_ARCH=arch-darwin-cxx-debug --download-scalapack=1
--download-blacs=1
--with-mumps-dir=/Users/mahadevan/source/MUMPS_4.10.0-p3
--download-hypre=1 --with-metis=1 --with-parmetis=1
--known-mpi-shared-libraries=1
--with-blas-lapack-lib=/System/Library/Frameworks/vecLib.framework/vecLib
--with-c++-support=1 --with-c-support=1 --with-cc=mpicc
--with-clanguage=C++ --with-moab-dir=/opt/moab
--with-dynamic-loading=1 --with-fc=mpif90 --with-fortran=1
--with-mpi=1 --with-shared-libraries=1 --with-valgrind=1
--with-valgrind-dir=/opt/local --with-cc=mpicc --with-cxx=mpicxx
COPTFLAGS="-g -fPIC" CXXOPTFLAGS="-g -fPIC" FOPTFLAGS="-g -fPIC"
--with-metis-dir=/usr/local --with-parmetis-dir=/usr/local
--with-netcdf-dir=/usr/local --with-zoltan=1
--with-zoltan-lib="-L/usr/local/lib -lptscotch -lscotch -lscotchmetis
-lscotcherr -lscotcherrexit -lzoltan"
--with-zoltan-include=/usr/local/include --with-hdf5
--with-hdf5-include=/usr/local/include
--with-hdf5-lib="-L/usr/local/lib -lhdf5_fortran -lhdf5"
--with-netcdf-dir=/usr/local --with-cmake=/opt/local/bin/cmake
--with-x-dir=/opt/local
[0]PETSC ERROR:
------------------------------------------------------------------------
[0]PETSC ERROR: PetscLayoutSetBlockSize() line 459 in
/Users/mahadevan/source/petsc-dev/src/vec/is/utils/pmap.c
[0]PETSC ERROR: VecSetBlockSize() line 1471 in
/Users/mahadevan/source/petsc-dev/src/vec/vec/interface/vector.c
[0]PETSC ERROR: main() line 32 in src/vec/vec/examples/tests/ex1.c

Thanks,
Vijay