Dear Jed and Matt and all, In the meantime, I implemented idea no. 1:
On Wed, 15 Oct 2008, Tim Kroeger wrote: > 1. I could do MatShellSetOperation(A,MATOP_GET_DIAGONAL,...), which is easy > in my case and should enable PETSc to do at least JACOBI preconditioning for > that matrix, shouldn't it? This seems to work fine for my example at the moment. Thank you very much again for your help. I might come back to the other suggestions/ideas if I encounter new problems when my example becomes more complicated. Best Regards, Tim -- Dr. Tim Kroeger Phone +49-421-218-7710 tim.kroeger at mevis.de, tim.kroeger at cevis.uni-bremen.de Fax +49-421-218-4236 MeVis Research GmbH, Universitaetsallee 29, 28359 Bremen, Germany Amtsgericht Bremen HRB 16222 Geschaeftsfuehrer: Prof. Dr. H.-O. Peitgen
