Dear petsc users, I have a question to ask for your suggestions which is to solve Ax=b using GMRES, here A is partially dense. Using petsc, I successfully used the matrix-free approach to solve it so that the expensive storage of A is avoided. My question is could I offer an matrix B (which is sparse matrix and good approximation to A) so that the convergence rate of GMRES can be speed up.
Best wishes Zhengyong -- Zhengyong Ren AUG Group, Institute of Geophysics Department of Geosciences, ETH Zurich NO H 47 Sonneggstrasse 5 CH-8092, Z?rich, Switzerland Tel: +41 44 633 37561 e-mail: zhengyong.ren at aug.ig.erdw.ethz.ch Gmail: renzhengyong at gmail.com -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.mcs.anl.gov/pipermail/petsc-users/attachments/20120403/18eb0fae/attachment.htm>
