From 999b3cf7a5b4537647f34b4bf5e43ccef2ec1be3 Mon Sep 17 00:00:00 2001
From: Martin Kronbichler <kronbichler@lnm.mw.tum.de>
Date: Sat, 3 Jun 2017 16:51:00 +0200
Subject: [PATCH] Fix bug in eulerian mapping regarding preservation of vertex
 locations

---
 include/deal.II/fe/mapping_q_eulerian.h | 9 +++++++++
 source/fe/mapping_q_eulerian.cc         | 9 +++++++++
 2 files changed, 18 insertions(+)

diff --git a/include/deal.II/fe/mapping_q_eulerian.h b/include/deal.II/fe/mapping_q_eulerian.h
index d21ca6ce4b..96613488ba 100644
--- a/include/deal.II/fe/mapping_q_eulerian.h
+++ b/include/deal.II/fe/mapping_q_eulerian.h
@@ -129,6 +129,7 @@ public:
    * preserve vertex locations (unless the translation vector happens to
    * provide for zero displacements at vertex locations).
    */
+  virtual
   bool preserves_vertex_locations () const;
 
   /**
@@ -200,6 +201,14 @@ private:
     std::vector<Point<spacedim> >
     compute_mapping_support_points(const typename Triangulation<dim,spacedim>::cell_iterator &cell) const;
 
+    /**
+     * Always returns @p false because MappingQ1Eulerian does not in general
+     * preserve vertex locations (unless the translation vector happens to
+     * provide for zero displacements at vertex locations).
+     */
+    virtual
+    bool preserves_vertex_locations () const;
+
   private:
     /**
      * Reference to the surrounding object off of which we live.
diff --git a/source/fe/mapping_q_eulerian.cc b/source/fe/mapping_q_eulerian.cc
index bd9f65ffc2..39250e5d7a 100644
--- a/source/fe/mapping_q_eulerian.cc
+++ b/source/fe/mapping_q_eulerian.cc
@@ -153,6 +153,15 @@ get_vertices
 
 
 
+template <int dim, class VectorType, int spacedim>
+bool
+MappingQEulerian<dim, VectorType, spacedim>::MappingQEulerianGeneric::
+preserves_vertex_locations () const
+{
+  return false;
+}
+
+
 
 template <int dim, class VectorType, int spacedim>
 std::vector<Point<spacedim> >
-- 
2.39.5