The multigrid PC needs information about the grid and discretization. If you cannot provide this, use AMG through Hypre or ML. Or if you have a structured grid, consider using DMMG.
Thanks, Matt On 8/15/07, Ben Tay <zonexo at gmail.com> wrote: > Hi, > > I found that there's a multigrid option in the manual which can be used > by adding -pctype mg -pcmgtype PC_MG_MULTIPLICATIVE. > > However, it seems that I am actually just using LU since with or without > this option, I got exactly the same answer. Am I using multigrid the > wrong way? > > Thanks > > -- 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