On Wed, Mar 16, 2011 at 00:09, Barry Smith <bsmith at mcs.anl.gov> wrote:
> Why not pass your Mat (maybe a global MPIAIJ) as the mat and pass your > MatNest as your pmat and have some of the subblocks in the MatNest be > defined by submatrices of of the MPIAIJ matrix. That's what I had in mind. By retaining ownership, I mean get rid of this awkward MAT_INITIAL_MATRIX stuff, have the original matrix save the submatrix in a private table (isrow, iscol, submat), and return a reference. Then if two users ask for the same submatrix, it would only be extracted once and this reference would be returned. If you need an _exclusive_ copy of a submatrix (you plan to modify it in a way that would make shared copies incorrect), then you would copy it [1], but I think that is much more rare. [1] Or use a flag that says that you want an exclusive copy. -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.mcs.anl.gov/pipermail/petsc-dev/attachments/20110316/91db1fb3/attachment.html>
