Anders Logg wrote: > I'm looking at how to extend GenericSparsityPattern for parallel > assembly. > > Currently, the interface allows the number of nonzeros per row to be > retrieved when initializing a matrix (through the common interface). > > For PETSc, the interface needs to be extended to include both the > number of nonzeros in the diagonal block and offdiagonal blocks for > each row. This is already in the subclass SparsityPattern and a cast > is used in PETScMatrix to convert the GenericSparsityPattern to a > SparsityPattern so the offdiagonal nonzeros may be retrieved. > > For Epetra, we have a subclass EpetraSparsityPattern and also a cast > in EpetraMatrix. > > So, what would be a sensible way to design/implement the different > sparsity patterns? One option could be to extend > GenericSparsityPattern with the stuff needed for PETSc, and just have > those functions return an error for Epetra. There would then be a > single cast (in EpetraMatrix) and all backends except Epetra would use > the SparsityPattern implementation. If so, I can go ahead and make the > required changes so it works with PETSc. Epetra should work as is I > guess, assuming Epetra_FECrsGraph& does the right thing. > > On a side note, we build much more information in SparsityPattern than > we actually need for PETSc. We know all the nonzero columns but just > count the total number and throw away the more fine-grained > information. Is there a way to pass this on to PETSc and have PETSc > use it? >
This might be what you want. http://www.mcs.anl.gov/petsc/petsc-as/snapshots/petsc-current/docs/manualpages/Mat/MatSeqAIJSetColumnIndices.html#MatSeqAIJSetColumnIndices Garth > > > ------------------------------------------------------------------------ > > _______________________________________________ > DOLFIN-dev mailing list > DOLFIN-dev@fenics.org > http://www.fenics.org/mailman/listinfo/dolfin-dev _______________________________________________ DOLFIN-dev mailing list DOLFIN-dev@fenics.org http://www.fenics.org/mailman/listinfo/dolfin-dev
