Make Mapping::get_center() work with simplices.

include/deal.II/fe/mapping.h

@@ -348,7 +348,7 @@ class Mapping : public Subscriptor
     const typename Triangulation<dim, spacedim>::cell_iterator &cell) const;
 
   /**
-   * Return the mapped center of a cell.
+   * Return one of two possible mapped centers of a cell.
    *
    * If you are using a (bi-,tri-)linear mapping that preserves vertex
    * locations, this function simply returns the value also produced by
@@ -358,21 +358,21 @@ class Mapping : public Subscriptor
    * polynomials, for which the center may not coincide with the average of
    * the vertex locations.
    *
-   * By default, this function returns the push forward of the center of the
+   * By default, this function returns the push forward of the barycenter of the
    * reference cell. If the parameter
-   * @p map_center_of_reference_cell is set to false, than the return value
-   * will be the average of the vertex locations, as returned by the
+   * @p map_barycenter_of_reference_cell is set to false, than the returned
+   * value will be the average of the vertex locations, as returned by the
    * get_vertices() method.
    *
    * @param[in] cell The cell for which you want to compute the center
-   * @param[in] map_center_of_reference_cell A flag that switches the algorithm
-   * for the computation of the cell center from
+   * @param[in] map_barycenter_of_reference_cell A flag that switches the
+   * algorithm for the computation of the cell center from
    * transform_unit_to_real_cell() applied to the center of the reference cell
    * to computing the vertex averages.
    */
   virtual Point<spacedim>
   get_center(const typename Triangulation<dim, spacedim>::cell_iterator &cell,
-             const bool map_center_of_reference_cell = true) const;
+             const bool map_barycenter_of_reference_cell = true) const;
 
   /**
    * Return the bounding box of a mapped cell.

source/fe/mapping.cc

@@ -54,22 +54,20 @@ template <int dim, int spacedim>
 Point<spacedim>
 Mapping<dim, spacedim>::get_center(
   const typename Triangulation<dim, spacedim>::cell_iterator &cell,
-  const bool map_center_of_reference_cell) const
+  const bool map_barycenter_of_reference_cell) const
 {
-  if (map_center_of_reference_cell)
+  if (map_barycenter_of_reference_cell)
     {
-      Point<dim> reference_center;
-      for (unsigned int d = 0; d < dim; ++d)
-        reference_center[d] = .5;
-      return transform_unit_to_real_cell(cell, reference_center);
+      return transform_unit_to_real_cell(
+        cell, cell->reference_cell().template barycenter<dim>());
     }
   else
     {
       const auto      vertices = get_vertices(cell);
       Point<spacedim> center;
       for (const auto &v : vertices)
         center += v;
-      return center / GeometryInfo<dim>::vertices_per_cell;
+      return center / cell->n_vertices();
     }
 }