On Wed, Jun 15, 2011 at 19:35, Alexander Grayver <agrayver at gfz-potsdam.de>wrote:
> Actually, I'm going to use this product as a part of the following > expressions: > > v'*A'*A*v > A'*A*v > Two choices here w = A*v result1 = norm(w) result2 = A'*w preprocess: B = A'*A w = B*v result1 = dot(v,w) result2 = w Note that B will require a bit more storage it is less sparse. It is probably problem-dependent which of these is faster. -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.mcs.anl.gov/pipermail/petsc-users/attachments/20110615/93516b31/attachment-0001.htm>
