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git-svn-id: https://svn.dealii.org/trunk@2535 0785d39b-7218-0410-832d-ea1e28bc413d

diff --git a/deal.II/deal.II/source/dofs/dof_renumbering.cc b/deal.II/deal.II/source/dofs/dof_renumbering.cc
index c93958442314f94248e11b5a25c47829a8fc5497..2856331c4d1ca390d3c52cb26a2281737a8f50f7 100644 (file)
--- a/deal.II/deal.II/source/dofs/dof_renumbering.cc
+++ b/deal.II/deal.II/source/dofs/dof_renumbering.cc
@@ -163,7 +163,7 @@ void DoFRenumbering::Cuthill_McKee (DoFHandler<dim>            &dof_handler,
        continue;
 
 
-// store for each coordination
+                                      // store for each coordination
                                       // number the dofs with these
                                       // coordination number
       multimap<unsigned int, int> dofs_by_coordination;
@@ -187,7 +187,9 @@ void DoFRenumbering::Cuthill_McKee (DoFHandler<dim>            &dof_handler,
          dofs_by_coordination.insert (new_entry);
        };
       
-                                      ////
+                                      // assign new DoF numbers to
+                                      // the elements of the present
+                                      // front:
       multimap<unsigned int, int>::iterator i;
       for (i = dofs_by_coordination.begin(); i!=dofs_by_coordination.end(); ++i) 
        new_number[i->second] = next_free_number++;
@@ -200,8 +202,25 @@ void DoFRenumbering::Cuthill_McKee (DoFHandler<dim>            &dof_handler,
 //TODO: Allow incomplete renumbering for non-discretization values
 
 #ifdef DEBUG
-                                  //  test for all indices numbered
-  if (find (new_number.begin(), new_number.end(), DoFHandler<dim>::invalid_dof_index) != new_number.end())
+                                  // test for all indices
+                                  // numbered. this mostly tests
+                                  // whether the
+                                  // front-marching-algorithm (which
+                                  // Cuthill-McKee actually is) has
+                                  // reached all points. it should
+                                  // usually do so, but might not for
+                                  // two reasons:
+                                  //
+                                  // - The algorithm above has a bug, or
+                                  // - The domain is not connected and
+                                  // consists of separate parts.
+                                  //
+                                  // In any case, if not all DoFs
+                                  // have been reached, renumbering
+                                  // will not be possible
+  if (find (new_number.begin(), new_number.end(), DoFHandler<dim>::invalid_dof_index)
+      !=
+      new_number.end())
     Assert (false, ExcRenumberingIncomplete());
   Assert (next_free_number == n_dofs,
          ExcRenumberingIncomplete());