Are there any examples that show how to use the ML PC? 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 -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.mcs.anl.gov/pipermail/petsc-users/attachments/20101203/7d462808/attachment.htm>
