Dear Markus,
> I am trying to solve Laplace with Neumann boundary conditions (step-11). I > implemented it the following way: > ... > Unfortunately the cg-method does not converge. What do I have to change to > get > this program running? I can't see anything that looks strange in your code. The usual case when CG does not converge is when you have a non-symmetric matrix or a non-symmetric preconditioner. SSOR without (parallel) overlap results in a symmetric preconditioner, so CG should be fine. My guess is that there is something wrong with the matrix. Can you check the part of your code where you build the small matrix? Do you do anything with the matrix after assembly (like applying Dirichlet conditions, etc)? Best regards, Martin _______________________________________________ dealii mailing list http://poisson.dealii.org/mailman/listinfo/dealii
