I need do it for many. Actually, we don't consider a vector. Generally, if A is dense matrix (nonzero entries) and B is sparse matrix, MatGetRow() doesn't work when doing A.*B or A./B directly, right? Thanks a lot.
Regards, Yujie On Sun, Feb 21, 2010 at 2:41 PM, Jed Brown <jed at 59a2.org> wrote: > On Sun, 21 Feb 2010 14:33:23 -0600, Yujie <recrusader at gmail.com> wrote: > > Thanks very much, Jed. > > I have a vector (V) and a matrix (A), > > I want to do Row_i_A.*V or Row_i_A./V (Row_i_A are the rows of A). > However, > > V has different format with the rows of A. > > You need to do this for a small number of rows (values of i), or for > many? Since vectors are dense, and since MatGetValues only provides the > local part, this is not scalable. > > What is the problem you are trying to solve with this algebraic > manipulation? There is probably a scalable way to formulate the > higher-level objective to avoid these shenanigans. > > Jed > -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.mcs.anl.gov/pipermail/petsc-users/attachments/20100221/f099979b/attachment.htm>
