[petsc-users] Setting block size for MPI vectors

[Vijay S. Mahadevan]

Thanks Barry. Yes, I tried that sequence and it works. But curiously
if I call VecSetBlockSize after VecSetType, it does fails with the
same error.

Would it be useful to take block size as a user input in VecCreateMPI
to be consistent with VecCreateMPIWithArray ? Just a thought. For now,
I will stick with the long winded way.

Vijay

On Tue, Aug 27, 2013 at 4:49 PM, Barry Smith <bsmith at mcs.anl.gov> wrote:
>
>    You need to use the "long winded" construction of vectors to add these options. For example,
>
>     VecCreate()
>     VecSetBlockSize()
>     VecSetSizes()
>     VecSetType()
>
>   the reason is that the Vec may be constructed differently based on these options but the VecCreateMPI() is suppose to produce an already constructed Vec.
>
>    Barry
>
>
> On Aug 27, 2013, at 4:45 PM, "Vijay S. Mahadevan" <vijay.m at gmail.com> wrote:
>
>> 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
>