From f7b00ceb393947f88fce1e927aed8bfd14cdf771 Mon Sep 17 00:00:00 2001
From: Martin Kronbichler <kronbichler@lnm.mw.tum.de>
Date: Sat, 5 Dec 2015 10:41:14 +0100
Subject: [PATCH] Fix quadratic complexity inside
 p::d::Tria::fill_vertices_with_ghost_neighbors

---
 doc/news/changes.h         | 10 ++++++++++
 source/distributed/tria.cc |  4 ++--
 2 files changed, 12 insertions(+), 2 deletions(-)

diff --git a/doc/news/changes.h b/doc/news/changes.h
index e8afbbf7ea..506d671b47 100644
--- a/doc/news/changes.h
+++ b/doc/news/changes.h
@@ -451,6 +451,16 @@ inconvenience this causes.
 
 
 <ol>
+  <li> Improved: The method
+  parallel::distributed::Triangulation::fill_vertices_with_ghost_neighbors
+  that is used for distributing DoFs on parallel triangulations previously
+  exhibited quadratic complexity in the number of coarse grid cells. This has
+  been changed into linear complexity calls (apart from a few issues
+  inside p4est).
+  <br>
+  (Martin Kronbichler, 2015/12/05)
+  </li>
+
   <li> Fixed: The constructor of SymmetricTensor that takes an array
   of initializing elements led to a compiler error. This is now
   fixed.
diff --git a/source/distributed/tria.cc b/source/distributed/tria.cc
index c05b7dd64c..160f40ea62 100644
--- a/source/distributed/tria.cc
+++ b/source/distributed/tria.cc
@@ -4810,8 +4810,8 @@ namespace parallel
     {
       int i, l = quad.level;
       int child_id;
-      const std::vector<types::global_dof_index> perm = triangulation->get_p4est_tree_to_coarse_cell_permutation ();
-      types::global_dof_index dealii_index = perm[treeidx];
+      types::global_dof_index dealii_index =
+        triangulation->get_p4est_tree_to_coarse_cell_permutation()[treeidx];
 
       for (i = 0; i < l; i++)
         {
-- 
2.39.5