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 > >> > > > > >
