Solver problem

Andreas Grassl Andreas.Grassl at
Tue Jul 28 02:30:46 CDT 2009

Tim Kroeger schrieb:
> Would you recommend to try MUMPS as well?  (I.e., will MUMPS have a
> change to be faster than ILU?)

I would highly recommend to give it a try.

MUMPS is a direct sparse solver, so it is not comparable to the combination
ilu-gmres, because iterative solver have a complexity of O(N) and highly depend
on the spectrum/condition of the matrix. Sparse direct solver have a complexity
of around O(N^2), but the runtime is not connected to the condition of the
matrix (only the accuracy of the result).

In my experience MUMPS is much faster than lu, because lu is only sequential and
the implementation is only for "verification"-reasons, what i understood.

Maybe -ksp_monitor_singular_value is interesting for you?

 /"\                               Grassl Andreas
 \ /    ASCII Ribbon Campaign      Uni Innsbruck Institut f. Mathematik
  X      against HTML email        Technikerstr. 13 Zi 709
 / \                               +43 (0)512 507 6091

More information about the petsc-users mailing list