Manav, If your matrix can be stored as BAIJ with dense blocks, then using BAIJ would be more memory efficient. See slides 42 of http://www-unix.mcs.anl.gov/petsc/petsc-as/documentation/tutorials/LCRC-06.pdf.
Hong On Sun, 28 Sep 2008, Manav Bhatia wrote: > One more question: > When is it advantageous to use BAIJ format instead of AIJ? > > Thanks, > Manav > > > On Sep 28, 2008, at 3:48 PM, Manav Bhatia wrote: > >> Hi, >> >> I have a few questions about the block format matrix. >> >> In the function: MatCreateSeqBAIJ, the arguments are >> >> bs - size of block >> m - number of rows >> n - number of columns >> nz - number of nonzero blocks per block row (same for all rows) >> nnz - array containing the number of nonzero blocks in the various block >> rows (possibly different for each block row) or PETSC_NULL >> >> If I specify the nnz vector, then what is the dimension of this vector? Is >> that equal to the block size? If so, then is it assumed that all blocks >> have the same number of non-zeros per row? >> >> If my blocks have different non-zero patterns, then should I use an AIJ >> format instead of a BAIJ format? >> >> Thanks, >> Manav >
