On Thu, Feb 03, 2011 at 09:03:58PM +0100, Niclas Jansson wrote: > Anders Logg <l...@simula.no> writes: > > > On Tue, Feb 01, 2011 at 11:57:28AM -0000, Anders Logg wrote: > >> Question #143645 on DOLFIN changed: > >> https://answers.launchpad.net/dolfin/+question/143645 > >> > >> Anders Logg proposed the following answer: > >> On Tue, Feb 01, 2011 at 11:50:37AM -0000, Garth Wells wrote: > >> > Question #143645 on DOLFIN changed: > >> > https://answers.launchpad.net/dolfin/+question/143645 > >> > > >> > Status: Open => Answered > >> > > >> > Garth Wells proposed the following answer: > >> > I don't think so. > >> > >> I think it should be possible, at least "in principle". I'll comment > >> more later. I'm in a meeting now. > > > > Sorry for my late reply. > > > > What you can do is to get the "overlap": > > > > std::map<uint, std::vector<uint> >* overlap = > > mesh.data().vector_mapping("overlap"); > > > > This gives you a mapping for each shared vertex to its neighboring > > processes (the processes it's shared with). > > > > You can check if a vertex is shared by > > > > overlap->find(i) != overlap->end() > > > > There is no functionality for checking edges, cells etc. Such > > operations must be expressed in terms of their vertices. > > > > It would be easy to add some shortcuts like > > > > bool Vertex::is_ shared() const; > > > > and even > > > > bool MeshEntity::is_shared() const; > > > > etc if that helps. They could just look at the overlap. > > > > If that is costly, we could store another MeshFunction that holds the > > appropriate data (or add as part of ParallelData). > > > > > > Perfect! That should be enough to get me started porting some code.
Great! > How about owners of mesh entities? If I remember correctly mesh entities > were not owned by a specific rank. If one could determine if a vertex > is owned, ghosted or shared, it would make life much simpler when > implementing various parallel mesh algorithms. Isn't the rule that when a vertex is shared, it's owned by the lowest rank process? I don't know how we handle ghosted entities (or if we even have ghosted entities). We have ghosted dofs stored in Vectors (handled by PETSc/Epetra) but I'm not sure how it's handled. Garth knows a great deal more about that. -- Anders _______________________________________________ Mailing list: https://launchpad.net/~dolfin Post to : dolfin@lists.launchpad.net Unsubscribe : https://launchpad.net/~dolfin More help : https://help.launchpad.net/ListHelp
