On Apr 15, 2013, at 5:55 PM, Matthew Knepley wrote: > On Mon, Apr 15, 2013 at 10:52 AM, Hui Zhang <mike.hui.zhang at hotmail.com> > wrote: > I'm implementing a domain decomposition preconditioner. The dof is ordered > by myapp and using AO (and LocalToGlobalMapping for assembly) to map to petsc > ordering. > The task I'm doing is building VecScatter's from subdomains to the global > domain. So my program is > > I do not understand why you would need AOs for this. They are for global > reordering, whereas you seem to only > need a local mapping here.
Thanks a lot! I see the difference now. > > Matt > > Step 1. I can map subdomain petsc ordering to subdomain natural ordering. > > Step 2. I can also map subdomain natural ordering to global domain natural > ordering. > > Step 3. I have an AO for mapping global domain natural ordering to petsc > ordering. > > Since each subdomain is defined on a sub-communicator of the communicator of > the global domain. My question is for > > AOApplicationToPetscIS(AO ao,IS is) > > can ao and is have different communicators? Will my program be bad for large > problems? How would you do it? > > > > -- > 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
