On Wed, Apr 6, 2011 at 2:01 PM, Jed Brown <jed at 59a2.org> wrote: > 2011/4/6 Gong Ding <gdiso at ustc.edu> > >> Ok, I will investigate matrix null space problem. >> The matrix comes from nonlinear problem, I wonder if I need to calculate >> the eigenvector each time. >> > > Possibly, but it is more likely that the null space is something simple > like a constant. > > >> >> Several months ago, some one committed DGMRES implementation, which also >> dropped smallest eigen value. >> It it possible to use (slightly modified) DGMRES as flexable tool for >> sigular problem? >> > > I'm not familiar with DGMRES. >
Deflated GMRES will not help here. This is just the power method, and thus gets the large eigenvalues first. You will not get the null space vector. Matt -- What most experimenters take for granted before they begin their experiments is infinitely more interesting than any results to which their experiments lead. -- Norbert Wiener -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.mcs.anl.gov/pipermail/petsc-users/attachments/20110406/344b96eb/attachment.htm>
