On Dec 17, 2012, at 4:59 PM, Stefano Zampini <stefano.zampini at gmail.com> wrote:
> I need a 1-coloring algorithm to implement a Deluxe version of BDDC, where > the partition of unity is realized by solving coupled subdomain problems. I > completely understand Barry's point about adding a different kind of coloring > to a library devoted to Nonlinear solvers, but using MatColoring only for > Jacobian computations is at least ambiguous; MatColoringType could carry > information about the type of coloring (distance-1, distance-2 star, acyclic > etc), MatColoringOrderingorWhatever contain the kind of ordering (ID, SL, LF > ..) We use the term Type in PETSc to represent subclasses (different implementations to achieve the same task)*, thus currently MatColoringType is sl, sf etc. It would be confusing to change it to mean something else so we need another term. Maybe MatColoringProblemType() ? Other suggestions? And I totally agree we should have these other colorings available to PETSc. Barry * One could argue that the current model of XXXSetType() is stupid and we should change it to XXXSetSubClasse() or something, but I doubt that will happen :-) > > > 2012/12/17 Barry Smith <bsmith at mcs.anl.gov> > > On Dec 17, 2012, at 2:56 PM, Jed Brown <jedbrown at mcs.anl.gov> wrote: > > > Stefano wants it to solve face-centered subdomain problems. The same > > structure also shows up in local processing for multiscale finite elements. > > Like in a multiplicative Schwarz kind of way? That is fine but completely > different than what 2 colorings are for. > > Barry > > > > > > > On Mon, Dec 17, 2012 at 1:16 PM, Barry Smith <bsmith at mcs.anl.gov> wrote: > > > > On Dec 17, 2012, at 1:49 PM, Jed Brown <issues-reply at bitbucket.org> > > wrote: > > > > What is the 1 coloring used for? The 2-coloring is for computing > > Jacobians, not for other stuff. It is not clear to me that both colorings > > should be hidden behind the same method names, calling sequence etc if they > > are used for very different purposes. So think before blindly implementing > > a 1 coloring algorithm onto of what is already there. > > > > Barry > > > > > --- you can reply above this line --- > > > > > > New issue 25: Add support for 1-coloring instead of only 2-coloring > > > https://bitbucket.org/petsc/petsc-dev/issue/25/add-support-for-1-coloring-instead-of-only > > > > > > Jed Brown: > > > > > > `MatGetColoring()` computes a coloring of `A^T A`, which is a 2-coloring > > > of the graph `A`. Support for a 1-coloring would also be useful. > > > > > > > > > -- > > > > > > This is an issue notification from bitbucket.org. You are receiving > > > this either because you are the owner of the issue, or you are > > > following the issue. > > > > > > > > > > > > > > -- > Stefano
