Dear Ellen, you may want to compare with this:
https://github.com/luca-heltai/dealii/pull/91/files#diff-acfb3c7b43e4935be016fda6ebdc5881 It is a parallel version of step-38, that never got into the library, written by one of our students, during a deal.II workshop in Trieste (held by Timo and myself). Best, Luca. > On 21 Dec 2019, at 20:52, Ellen M. Price <ellen.pric...@gmail.com> wrote: > > Thanks for the feedback. This problem was me writing to the wrong matrix > elements, and I'm so close to having a working prototype of this code. I > think the (hopefully last) bug is in this section of code: > > dof_handler.clear(); > dof_handler.distribute_dofs(fe); > locally_owned_dofs = dof_handler.locally_owned_dofs(); > DoFTools::extract_locally_relevant_dofs(dof_handler, locally_relevant_dofs); > > DynamicSparsityPattern dsp(locally_relevant_dofs); > DoFTools::make_sparsity_pattern(dof_handler, dsp); > SparsityTools::distribute_sparsity_pattern( > dsp, dof_handler.n_locally_owned_dofs_per_processor(), > MPI_COMM_WORLD, locally_relevant_dofs); > > system_matrix.reinit(locally_owned_dofs, locally_owned_dofs, > dsp, MPI_COMM_WORLD); > > current_solution.reinit(locally_owned_dofs, > locally_relevant_dofs, MPI_COMM_WORLD); > right_hand_side.reinit(locally_owned_dofs, MPI_COMM_WORLD); > > I get a runtime exception from the TrilinosWrappers module when I call > SparseMatrix::add() on more than one processor, and I suspect that I've set > up the sparsity pattern incorrectly (maybe the system_matrix doesn't know how > to distribute entries, or it gets the wrong indices?). Is there anything > obviously wrong with what I've done here? There are a lot of notes in the > doxygen about setting up the Trilinos sparsity pattern, but nothing I've > tried (like calling compress() after setting up the matrix) works. > > Ellen > > > On Friday, December 20, 2019 at 10:24:23 PM UTC-6, Wolfgang Bangerth wrote: > On 12/20/19 6:42 PM, Ellen M. Price wrote: > > I did eventually solve this problem, but I ran into another one. I think > > I'm > > close, I just need a little guidance. The problems occur in assembling the > > system. I've checked the right-hand side vector and it has some odd > > features. > > I'm running the "slide" problem, just like step-33 does. I suppose my > > question > > is, how should the system assembly routine be changed to accommodate > > parallelization? All I did was add an if statement to check whether a cell > > is > > locally owned before computing on it. Conceptually, what else needs to > > change? > > Ellen, > not actually very much: You need a non-ghosted (writable) vector, which > apparently you have, for your right hand side. Then you loop over the locally > owned cells (which you do), and the only other thing you have to do is to > call > compress() at the end of the assembly. > > There are many other things one can do to test whether things work correctly, > but "has some odd features" is not enough of a hint to allow for more > concrete > suggestions :-) > > Best > WB > > > -- > ------------------------------------------------------------------------ > Wolfgang Bangerth email: bang...@colostate.edu > www: http://www.math.colostate.edu/~bangerth/ > > > -- > The deal.II project is located at http://www.dealii.org/ > For mailing list/forum options, see > https://groups.google.com/d/forum/dealii?hl=en > --- > You received this message because you are subscribed to the Google Groups > "deal.II User Group" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to dealii+unsubscr...@googlegroups.com. > To view this discussion on the web visit > https://groups.google.com/d/msgid/dealii/9b404d3e-cd78-4290-b4d0-11b36edcc692%40googlegroups.com. -- The deal.II project is located at http://www.dealii.org/ For mailing list/forum options, see https://groups.google.com/d/forum/dealii?hl=en --- You received this message because you are subscribed to the Google Groups "deal.II User Group" group. To unsubscribe from this group and stop receiving emails from it, send an email to dealii+unsubscr...@googlegroups.com. To view this discussion on the web visit https://groups.google.com/d/msgid/dealii/F4DAD081-B863-4B80-8AF9-42642DE67884%40gmail.com.
