On Sun, Jan 23, 2011 at 03:39, Gaurish Telang <gaurish108 at gmail.com> wrote:
> But for this I had to compute U(transpose)U explicitly. The algorithm > mentioned in the paper does NOT involve an explicit computation of > U(transpose)U. > > Is there a way to avoid the explicit and expensive computation of > U(transpose)U and use KSPLSQR? The details on this page > The need for explicit U^T U is for algebraic preconditioners (like incomplete factorization). You can try using cheaper approximations to this product or use a PCShell if you want to avoid explicitly forming the product. Chances are that unpreconditioned LSQR will converge too slowly. -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.mcs.anl.gov/pipermail/petsc-users/attachments/20110123/ae89f6f5/attachment.htm>
