Update documentation.

git-svn-id: https://svn.dealii.org/trunk@23623 0785d39b-7218-0410-832d-ea1e28bc413d

diff --git a/deal.II/include/deal.II/fe/fe_values.h b/deal.II/include/deal.II/fe/fe_values.h
index 448699d11151d127b62dad9d5fd234cb9666620d..2f1cfa491153d3e4d8f1d2c37d860e51d234a9bb 100644 (file)
--- a/deal.II/include/deal.II/fe/fe_values.h
+++ b/deal.II/include/deal.II/fe/fe_values.h
@@ -1002,6 +1002,23 @@ namespace FEValuesViews
                                    * element. Views are discussed in the
                                    * @ref vector_valued module.
                                    *
+                                   * This class allows to query the
+                                   * value and divergence of
+                                   * (components of) shape functions
+                                   * and solutions representing
+                                   * symmetric tensors. The
+                                   * divergence of a symmetric tensor
+                                   * $S_{ij}, 0\le i,j<\text{dim}$ is
+                                   * defined as
+                                   * $d_i = \sum_j \frac{\partial S_{ij}{\partial x_j},
+                                   * 0\le i<\text{dim}$,
+                                   * which due to the symmetry of the tensor is also
+                                   * $d_i = \sum_j \frac{\partial S_{ji}{\partial x_j}$.
+                                   * In other words, it due to the symmetry
+                                   * of $S$ it does not matter whether
+                                   * we apply the nabla operator by row
+                                   * or by column to get the divergence.
+                                   *
                                    * @ingroup feaccess vector_valued
                                    *
                                    * @author Andrew McBride, 2009
@@ -1028,6 +1045,11 @@ namespace FEValuesViews
                                        * of the finite element representing a symmetric second-order
                                        * tensor, the divergence of
                                        * course is a * <code>Tensor@<1,dim@></code>.
+                                       *
+                                       * See the general discussion
+                                       * of this class for a
+                                       * definition of the
+                                       * divergence.
                                        */
       typedef Tensor<1, spacedim> divergence_type;
 
@@ -1085,6 +1107,11 @@ namespace FEValuesViews
                                        * this view, for the shape function
                                        * and quadrature point selected by the
                                        * arguments.
+                                       *
+                                       * See the general discussion
+                                       * of this class for a
+                                       * definition of the
+                                       * divergence.
                                        */
       divergence_type
       divergence(const unsigned int shape_function,
@@ -1129,6 +1156,11 @@ namespace FEValuesViews
                                        * information can be obtained from
                                        * FEValuesBase::get_function_gradients,
                                        * of course.
+                                       *
+                                       * See the general discussion
+                                       * of this class for a
+                                       * definition of the
+                                       * divergence.
                                        */
       template <class InputVector>
       void get_function_divergences(const InputVector& fe_function,
@@ -2584,7 +2616,7 @@ class FEValuesBase : protected FEValuesData<dim,spacedim>,
 
                                     /// @name Geometry of the cell
                                     //@{
-    
+
                                     /**
                                      * Position of the <tt>i</tt>th
                                      * quadrature point in real space.
@@ -2710,7 +2742,7 @@ class FEValuesBase : protected FEValuesData<dim,spacedim>,
     void transform (std::vector<Tensor<1,spacedim> >& transformed,
                    const std::vector<Tensor<1,dim> >& original,
                    MappingType mapping) const;
-    
+
                                     /**
                                      * @deprecated Use
                                      * normal_vector() instead.
@@ -2781,7 +2813,7 @@ class FEValuesBase : protected FEValuesData<dim,spacedim>,
 
                                     /// @name Access to the raw data
                                     //@{
-    
+
                                     /**
                                      * Constant reference to the
                                      * selected mapping object.
@@ -4262,7 +4294,7 @@ namespace FEValuesViews
       }
   }
 
-  
+
   template <int dim, int spacedim>
   inline
   typename SymmetricTensor<2, dim, spacedim>::divergence_type