MPIAIJ and MatSetValuesBlocked

[Ryan Yan]

Hi, Satish,
It is very illustrating!
Thank you very much!

Yan

On Mon, May 4, 2009 at 2:45 PM, Satish Balay <balay at mcs.anl.gov> wrote:

> If you have a 3x3 block [i.e 9 values]. And compare MatSetValues() vs
> MatSetValuesBlocked() - then the differences are:
>
> 1. 9 row,col indices provided for MatSetValues() vs 1-row,col index
> for the block
>
> 2. The internal code for MatSetValues might have to loop over all 9
> indices and do 9 searches/checks [for the correct location with the
> matrix]. In the MatSetValuesBlocked() case - its just 1 search/check -
> and all the 9 values copied into the internal structure..
>
> 3. there could potentiall be 9 function calls with MatSetValues() vs 1
> for MatSetValuesBlocked()
>
> Even if you have to format the data a bit [perhaps copy into array[9]]
> that overhead might be less than the loop-search/insert overhead of
> MatSetValues().
>
> Satish
>
> On Mon, 4 May 2009, Ryan Yan wrote:
>
> > Hi Barry,
> > My matrix is read from files stroing a matrix in the Block CRS format. So
> a
> > natural way to create the matrix is MPIBAIJ. However, if I want to
> > use MatSetValuesBlocked() for the newly created MPIBAIJ, I still need
> > to load a tempary arrary(from Block CRS file) with the length of
> blocksize^2
> > and pass it into the Matrix via MatSetValuesBlocked(). This process is
> > similar to the MatSetValues. Could you make a little bit more
> clarification
> > on why the MatSetValuesBlocked() have some advantage on blocked
> structure?
> >
> > Thanks,
> >
> > Yan
> >
> >
> >
> > On Fri, May 1, 2009 at 6:12 PM, Barry Smith <bsmith at mcs.anl.gov> wrote:
> >
> > >
> > >  Support for MatSetValuesBlocked() for AIJ matrices was added in PETSc
> > > 3.0.0
> > >
> > >  Note that if your matrix is truly blocked you should use BAIJ
> matrices, if
> > > your matrix is not truly blocked then there is no benefit to using
> > > MatSetValuesBlocked() it was added so people could easily switch
> between AIJ
> > > and BAIJ for testing.
> > >
> > >   Barry
> > >
> > >
> > > On May 1, 2009, at 5:04 PM, Ryan Yan wrote:
> > >
> > > Hi, all,
> > >> I am using MPIAIJ for my matrix A, but when I call the function
> > >> MatSetValuesBlocked, I got the error:
> > >>
> > >> PetscPrintf(PETSC_COMM_WORLD, "breakpoint 1\n");
> > >>               ierr =
> > >>
> MatSetValuesBlocked(A,1,&irow,1,(col_ind+icol),temp_vector,INSERT_VALUES);
> > >>  PetscPrintf(PETSC_COMM_WORLD, "breakpoint 2\n");
> > >>
> > >>
> > >> breakpoint 1
> > >> [0]PETSC ERROR: --------------------- Error Message
> > >> ------------------------------------
> > >> [0]PETSC ERROR: No support for this operation for this object type!
> > >> [0]PETSC ERROR: Mat type mpiaij!
> > >> [0]PETSC ERROR:
> > >>
> ------------------------------------------------------------------------
> > >> [0]PETSC ERROR: Petsc Release Version 2.3.3, Patch 15, Tue Sep 23
> 10:02:49
> > >> CDT 2008 HG revision: 31306062cd1a6f6a2496fccb4878f485c9b91760
> > >> [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/vyan2000/local/PPETSc/petsc-2.3.3-p15/src/ksp/ksp/examples/tutorials/ttt2/kspex1reader_binmpiaij
> > >> on a linux-gnu named vyan2000-linux by vyan2000 Fri May  1 17:58:48
> 2009
> > >> [0]PETSC ERROR: Libraries linked from
> > >> /home/vyan2000/local/PPETSc/petsc-2.3.3-p15/lib/linux-gnu-c-debug
> > >> [0]PETSC ERROR: Configure run at Thu Feb  5 21:10:10 2009
> > >> [0]PETSC ERROR: Configure options --with-mpi-dir=/usr/lib/
> > >> --with-debugger=gdb --with-shared=0 --download-hypre=1
> --download-parmetis=1
> > >> [0]PETSC ERROR:
> > >>
> ------------------------------------------------------------------------
> > >> [0]PETSC ERROR: MatSetValuesBlocked() line 1289 in
> > >> src/mat/interface/matrix.c
> > >> breakpoint 2
> > >>
> > >> Is it the reason that  MatSetValuesBlocked only works for MPIBAIJ or
> > >> SeqBAIJ?
> > >>
> > >> Thanks,
> > >>
> > >> Yan
> > >>
> > >
> > >
> >
>
>
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