Matthew Knepley wrote: > That is strange. Your parallel SOR should be a stronger PC than the > Block-Jacobi SOR that PETSc is using. I have such hope and that was a motivation. I like to have algorithm which is efficient with large number of processors.
However, it is hard to prove > that restarted GMRES will converge, and thus this behavior is not > impossible. It is strange because with Block-Jacobi SOR convergence is ok. May be I should add some trick, f.e. add shift to diagonal. > > However, if you are using MG and the smoother is doing its job, you > should not take more than a few iterates. You should never get to > 30 outer GMRES iterates. > It is true, in practical computations I never have more than 30 iterations. However for tests, where I set error for small number (1e-12) number of iterations is more than 30. Regards, Lukasz
