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