Just reuse the old preconditioner. If you keep on making rank one changes then once the preconditioner starts performing poorly "start all over again" by building a new preconditioner from scratch. Only if this doesn't perform ok for some reason would I try anything more complicated.
Barry > On May 19, 2016, at 2:48 AM, Elias Karabelas <[email protected]> > wrote: > > Dear all, > > I have a question about preconditioned solvers. So, I have a Sparsematrix, > say A, and now for some reason I would like to add some rank-one term u v^T > to that matrix. > As far as I know about Petsc, I can define the action of this matrix with > MatShell. But is it possible to adapt the preconditioner (like a AMG) of my > KSP to handle that kind of MatShell? > > Kind Regards > Elias > > -- > Dr Elias Karabelas > > Medical University of Graz > Institute of Biophysics > Harrachgasse 21/IV > 8010 Graz, Austria > > Phone: +43 316 380 7759 > Email: [email protected] > Web : http://forschung.medunigraz.at/fodok/staff?name=EliasKarabelas >
