On Fri, Dec 3, 2010 at 12:33 PM, Randall Mackie <rlmackie862 at gmail.com>wrote:
> Are there any examples that show how to use the ML PC? > -pc_type ml It is Algebraic Multigrid. Matt > Randy > > > On Dec 3, 2010, at 9:02 AM, Matthew Knepley wrote: > > I will also note that a good intro for implementing your own might be the > ML PC > in Petsc. It puts the ML AMG package into the PCMG framework. > > Matt > > On Fri, Dec 3, 2010 at 3:44 AM, Dave May <dave.mayhem23 at gmail.com> wrote: > >> Hey Vijay, >> PCMG is generic. If you provide the operators for each level, along >> with the restriction and prolongation, >> you can use PCMG. It doesn't need to know about the mesh. >> >> You don't actually need to provide the coarse grid operators. >> Given the fine grid operator and R and optionally P, you can use >> Galerkin coarsening by calling >> PCMGSetGalerkin() or via the command line arg -pc_mg_galerkin >> Also, if you don't specify the prolongation, petsc will use P = R^T. >> >> >> Cheers, >> Dave >> >> >> On 3 December 2010 06:02, Vijay S. Mahadevan <vijay.m at gmail.com> wrote: >> > Hi all, >> > >> > I was wondering whether the MG preconditioner object is generic enough >> > to work out of the box like say ILU or SOR. To elaborate on this, if >> > I can provide the number of levels, restriction and prolongation >> > operators for each level and the system operators along with vectors >> > allocated for solution and rhs, would it work as a preconditioner for >> > my given problem and a prescribed rhs at the finest level of PCMG. Or >> > does it need some knowledge of the fine and coarser meshes to perform >> > the MG operations correctly ? >> > >> > All the examples I've seen using MG in petsc involve the DA and DMMG >> > objects and since I use my own mesh and corresponding discretization >> > code for an elliptic system, I'm curious about this usage. It would >> > not be terribly difficult to write my own framework to do a simple >> > V-cycle with my existing framework but since petsc already provides >> > this functionality along with different types of MG solves (with >> > verified code!), I really want to use it for my system. Any help >> > and/or pointers are welcome. >> > >> > Thanks, >> > vijay >> > >> > > > > -- > 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 > > > -- 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 -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.mcs.anl.gov/pipermail/petsc-users/attachments/20101203/bfeb03b6/attachment.htm>
