From 5cd3223e6ac87c8f3fb42a402f8671d50b567481 Mon Sep 17 00:00:00 2001
From: Wolfgang Bangerth <bangerth@math.tamu.edu>
Date: Tue, 21 Jan 2014 06:49:27 +0000
Subject: [PATCH] Clear active_fe_index flags on non-active cells since they
 have no meaning.

git-svn-id: https://svn.dealii.org/trunk@32273 0785d39b-7218-0410-832d-ea1e28bc413d
---
 deal.II/doc/news/changes.h       | 13 +++++++++++++
 deal.II/source/hp/dof_handler.cc |  8 ++++++++
 2 files changed, 21 insertions(+)

diff --git a/deal.II/doc/news/changes.h b/deal.II/doc/news/changes.h
index c21e09c334..69ee2024b2 100644
--- a/deal.II/doc/news/changes.h
+++ b/deal.II/doc/news/changes.h
@@ -84,6 +84,19 @@ inconvenience this causes.
 <h3>Specific improvements</h3>
 
 <ol>
+  <li> Changed: It was previously possible to set the
+  <code>active_fe_index</code> on non-active cells of an hp::DoFHandler.
+  However, this was prone to mistakes because it may lead to the assumption
+  that a finite element space out of the ones described by the hp::FECollection
+  associated with this hp::DoFHandler was actually associated with such
+  a cell. Since we do not actually distribute degrees of freedom for such
+  hp::DoFHandler objects on non-active cells, this is not the case. Consequently,
+  it no longer has any effect to assign active FE indices to non-active cells:
+  these values are simply reset later on.
+  <br>
+  (Wolfgang Bangerth, 2014/01/20)
+  </li>
+
   <li> Fixed: The method DoFTools::extract_constant_modes only worked for
   elements where the constant function 1 is represented by all ones. This
   is now fixed by querying the element for its constant modes on each cell.
diff --git a/deal.II/source/hp/dof_handler.cc b/deal.II/source/hp/dof_handler.cc
index 85a37b7aac..84bb3584e9 100644
--- a/deal.II/source/hp/dof_handler.cc
+++ b/deal.II/source/hp/dof_handler.cc
@@ -2600,6 +2600,14 @@ namespace hp
 
     finite_elements = &ff;
 
+    // nothing good can come off having active_fe_indices
+    // on non-active cells, since we do not distribute dofs
+    // there. kill these
+    for (cell_iterator cell = begin(); cell != end(); ++cell)
+      if (cell->has_children())
+        cell->set_active_fe_index (default_fe_index);
+
+
     // This call ensures that the
     // active_fe_indices vectors are
     // initialized correctly.
-- 
2.39.5