From: Wolfgang Bangerth <bangerth@math.tamu.edu>
Date: Fri, 12 Jun 2015 02:27:24 +0000 (-0500)
Subject: Allow Cuthill_McKee() to also use starting indices in parallel.
X-Git-Tag: v8.3.0-rc1~120^2~1
X-Git-Url: https://gitweb.dealii.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=9ef0529a6faef4b151aca7dfdbc4d678b141c9bb;p=dealii.git

Allow Cuthill_McKee() to also use starting indices in parallel.

This was previously not possible and likely yielded at best results that were not intended.
---

diff --git a/doc/news/changes.h b/doc/news/changes.h
index cdc18334f9..e2f743a95d 100644
--- a/doc/news/changes.h
+++ b/doc/news/changes.h
@@ -512,6 +512,12 @@ inconvenience this causes.
 <h3>Specific improvements</h3>
 
 <ol>
+  <li> Improved: DoFRenumbering::Cuthill_McKee() can now also
+  use starting indices for parallel triangulations.
+  <br>
+  (Wolfgang Bangerth, 2015/06/11)
+  </li>
+
   <li> Improved: VectorTools::interpolate now works with FE_Nothing.
   <br>
   (Angel Rodriguez, 2015/06/03)
diff --git a/source/dofs/dof_renumbering.cc b/source/dofs/dof_renumbering.cc
index d0cd8f6d4f..24ad40588d 100644
--- a/source/dofs/dof_renumbering.cc
+++ b/source/dofs/dof_renumbering.cc
@@ -431,9 +431,22 @@ namespace DoFRenumbering
                                  true);
           }
 
+        // translate starting indices from global to local indices
+        std::vector<types::global_dof_index> local_starting_indices (starting_indices.size());
+        for (unsigned int i=0; i<starting_indices.size(); ++i)
+          {
+            Assert (locally_owned.is_element (starting_indices[i]),
+                    ExcMessage ("You specified global degree of freedom "
+                                + Utilities::int_to_string(starting_indices[i]) +
+                                " as a starting index, but this index is not among the "
+                                "locally owned ones on this processor."));
+            local_starting_indices[i] = locally_owned.index_within_set(starting_indices[i]);
+          }
+
+        // then do the renumbering on the locally owned portion
         AssertDimension(new_indices.size(), locally_owned.n_elements());
         SparsityTools::reorder_Cuthill_McKee (sparsity, new_indices,
-                                              starting_indices);
+                                              local_starting_indices);
         if (reversed_numbering)
           new_indices = Utilities::reverse_permutation (new_indices);
 
diff --git a/tests/mpi/renumber_cuthill_mckee_02.cc b/tests/mpi/renumber_cuthill_mckee_02.cc
new file mode 100644
index 0000000000..1d0ea462c9
--- /dev/null
+++ b/tests/mpi/renumber_cuthill_mckee_02.cc
@@ -0,0 +1,122 @@
+// ---------------------------------------------------------------------
+//
+// Copyright (C) 2009 - 2014 by the deal.II authors
+//
+// This file is part of the deal.II library.
+//
+// The deal.II library is free software; you can use it, redistribute
+// it, and/or modify it under the terms of the GNU Lesser General
+// Public License as published by the Free Software Foundation; either
+// version 2.1 of the License, or (at your option) any later version.
+// The full text of the license can be found in the file LICENSE at
+// the top level of the deal.II distribution.
+//
+// ---------------------------------------------------------------------
+
+
+
+// Test that DofRenumbering::Cuthill_McKee works in parallel also when
+// a set of starting indices is given.
+
+
+#include "../tests.h"
+#include <deal.II/base/logstream.h>
+#include <deal.II/base/mpi.h>
+#include <deal.II/distributed/tria.h>
+#include <deal.II/grid/grid_generator.h>
+#include <deal.II/dofs/dof_handler.h>
+#include <deal.II/grid/tria_iterator.h>
+#include <deal.II/dofs/dof_accessor.h>
+#include <deal.II/dofs/dof_renumbering.h>
+#include <deal.II/fe/fe_q.h>
+
+#include <fstream>
+
+
+template<int dim>
+void test()
+{
+  unsigned int myid = Utilities::MPI::this_mpi_process (MPI_COMM_WORLD);
+  unsigned int nprocs = Utilities::MPI::n_mpi_processes (MPI_COMM_WORLD);
+
+  parallel::distributed::Triangulation<dim> tr (MPI_COMM_WORLD);
+
+  GridGenerator::hyper_cube (tr, -1.0, 1.0);
+  tr.refine_global (8-2*dim);
+
+  for (typename Triangulation<dim>::active_cell_iterator
+       cell = tr.begin_active();
+       cell != tr.end(); ++cell)
+    if (!cell->is_ghost() && !cell->is_artificial())
+      if (cell->center().norm() < 0.3)
+        {
+          cell->set_refine_flag();
+        }
+
+  tr.execute_coarsening_and_refinement ();
+
+  DoFHandler<dim> dofh (tr);
+
+  static const FE_Q<dim> fe (1);
+  dofh.distribute_dofs (fe);
+  std::vector<types::global_dof_index> renumbering(dofh.locally_owned_dofs().n_elements());
+  std::vector<types::global_dof_index> starting_indices;
+  starting_indices.push_back (dofh.locally_owned_dofs().nth_index_in_set(0));
+  DoFRenumbering::compute_Cuthill_McKee (renumbering, dofh, false, false, starting_indices);
+
+  // send everything to processor 0 for output
+  std::vector<types::global_dof_index> complete_renumbering(dofh.n_dofs());
+  std::copy(renumbering.begin(), renumbering.end(), complete_renumbering.begin());
+  unsigned int offset = renumbering.size();
+  for (unsigned int i=1; i<nprocs; ++i)
+    {
+      if (myid == i)
+        MPI_Send (&renumbering[0], renumbering.size(),
+                  Utilities::MPI::internal::mpi_type_id(&complete_renumbering[0]), 0, i,
+                  MPI_COMM_WORLD);
+      else if (myid == 0)
+        MPI_Recv (&complete_renumbering[offset],
+                  dofh.locally_owned_dofs_per_processor()[i].n_elements(),
+                  Utilities::MPI::internal::mpi_type_id(&complete_renumbering[0]), i, i,
+                  MPI_COMM_WORLD, MPI_STATUSES_IGNORE);
+      offset += dofh.locally_owned_dofs_per_processor()[i].n_elements();
+    }
+
+  if (myid == 0)
+    {
+      AssertDimension(offset, complete_renumbering.size());
+      for (unsigned int i=0; i<complete_renumbering.size(); ++i)
+        deallog << complete_renumbering[i] << std::endl;
+    }
+}
+
+
+int main (int argc, char *argv[])
+{
+  Utilities::MPI::MPI_InitFinalize mpi_initialization(argc, argv, 1);
+
+  unsigned int myid = Utilities::MPI::this_mpi_process (MPI_COMM_WORLD);
+
+
+  deallog.push (Utilities::int_to_string (myid));
+
+  if (myid == 0)
+    {
+      std::ofstream logfile ("output");
+      deallog.attach (logfile);
+      deallog.depth_console (0);
+      deallog.threshold_double (1.e-10);
+
+      deallog.push ("2d");
+      test<2>();
+      deallog.pop();
+      deallog.push ("3d");
+      test<3>();
+      deallog.pop();
+    }
+  else
+    {
+      test<2>();
+      test<3>();
+    }
+}
diff --git a/tests/mpi/renumber_cuthill_mckee_02.mpirun=4.output b/tests/mpi/renumber_cuthill_mckee_02.mpirun=4.output
new file mode 100644
index 0000000000..8d70654405
--- /dev/null
+++ b/tests/mpi/renumber_cuthill_mckee_02.mpirun=4.output
@@ -0,0 +1,471 @@
+
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+DEAL:0:3d::116
+DEAL:0:3d::117
+DEAL:0:3d::121
+DEAL:0:3d::118
+DEAL:0:3d::122
+DEAL:0:3d::119
+DEAL:0:3d::123
+DEAL:0:3d::120
+DEAL:0:3d::124