Sorry, I made a mistake, it should be A is sparse matrix and B is dense matrix.
Yujie On Sun, Feb 21, 2010 at 2:44 PM, Yujie <recrusader at gmail.com> wrote: > 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/20100221/83b0f1d9/attachment-0001.htm>
