On Mon, Jun 22, 2015 at 5:04 AM, Orxan Shibliyev <[email protected]> wrote:
> I wanted to compare my own GS and the one of PETSC's. I used KSPRICHARDSON > with PCSOR to obtain GS. I tested my GS with CFL=40 and solved Ax=b problem > successfully and fast. However, PETSC failed to solve at CFL=40 and it > gives an answer only for very low CFL numbers such as 0.1. Of course, the > convergence was very slow. My question is that if A and b and the > implementations are the same why PETSC fails to solve with same CFL number > as for my GS solver? > > PS1: My GS solver is a plain GS, no fancy stuff. > PS2: A is a block matrix (MATSEQBAIJ) for PETSC. Also, the process is > sequential. > 1) For any solver question, send the output of -ksp_view -ksp_monitor_true_residual -ksp_converged_reason 2) Did you use http://www.mcs.anl.gov/petsc/petsc-current/docs/manualpages/PC/PCSOR.html and set the options so that the algorithm matches yours? 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
