http://www.mcs.anl.gov/petsc/petsc-current/docs/manualpages/Mat/MatGetDiagonalBlock.html
On Wed, Jan 16, 2013 at 3:51 PM, Fande Kong <fd.kong at siat.ac.cn> wrote: > Thanks, Jed, > > Could I directly extract a local sub matrix from the parallel matrix? The > local part should be a sequential matrix. > > > On Wed, Jan 16, 2013 at 2:32 PM, Jed Brown <jedbrown at mcs.anl.gov> wrote: > >> 1. Partition the mesh >> 2. Create a sequential matrix representing local mesh adjacency >> 3. Use MATORDERINGRCM to get a new ordering for that sequential matrix >> 4. Broadcast the new global indices to neighbors >> >> >> On Wed, Jan 16, 2013 at 2:26 PM, Fande Kong <fd.kong at siat.ac.cn> wrote: >> >>> Barry, Thank you very much. >>> >>> What I want to do is to order the original mesh. I have partitioned the >>> mesh. But I want to reorder the vertices. Thus I create a matrix that >>> represent the relationships of the vertices, and then I want to use the >>> ordering methods in petsc to reorder the vertices by using matgetordering. >>> >>> What should I do if I want to use the ordering methods >>> (e.g. MATORDERINGRCM ) in petsc to reorder the mesh vertices? >>> >>> On Wed, Jan 16, 2013 at 1:10 PM, Barry Smith <bsmith at mcs.anl.gov> wrote: >>> >>>> >>>> On Jan 16, 2013, at 1:53 PM, Fande Kong <fd.kong at siat.ac.cn> wrote: >>>> >>>> > Hi all, >>>> > >>>> > I create a parallel mat with type MATMPIAIJ, and use the >>>> MatGetOrdering to reorder it. But it doesn't work. Who can tell me how to >>>> do that? I just want to reorder the local part of the matrix. >>>> >>>> We don't have code in place for this type of thing. Maybe if you >>>> explain why you would like it we could suggest alternatives. >>>> >>>> Generally we recommend ordering the original mesh appropriately so >>>> that the resulting matrices have good orderings and don't recommend >>>> reordering the matrices directly (except for direct solvers). >>>> >>>> Barry >>>> >>>> > >>>> > Thanks, >>>> > >>>> > -- >>>> > Fande Kong >>>> > ShenZhen Institutes of Advanced Technology >>>> > Chinese Academy of Sciences >>>> >>>> >>>> >>> >>> >>> -- >>> Fande Kong >>> ShenZhen Institutes of Advanced Technology >>> Chinese Academy of Sciences >>> >> >> > > > -- > Fande Kong > ShenZhen Institutes of Advanced Technology > Chinese Academy of Sciences > -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.mcs.anl.gov/pipermail/petsc-users/attachments/20130116/f052f529/attachment.html>
