Augment documentation

diff --git a/include/deal.II/multigrid/mg_transfer.h b/include/deal.II/multigrid/mg_transfer.h
index 89e3f57360cb2f7dec72ff087c218a436a00a0c8..2dc701135f89acc5a5f7a46d9bee7544427fa624 100644 (file)
--- a/include/deal.II/multigrid/mg_transfer.h
+++ b/include/deal.II/multigrid/mg_transfer.h
@@ -460,10 +460,36 @@ public:
   template <int dim, int spacedim>
   void build_matrices (const DoFHandler<dim,spacedim> &mg_dof);
 
+  /**
+   * Prolongate a vector from level <tt>to_level-1</tt> to level
+   * <tt>to_level</tt> using the embedding matrices of the underlying finite
+   * element. The previous content of <tt>dst</tt> is overwritten.
+   *
+   * @arg src is a vector with as many elements as there are degrees of
+   * freedom on the coarser level involved.
+   *
+   * @arg dst has as many elements as there are degrees of freedom on the
+   * finer level.
+   */
   virtual void prolongate (const unsigned int to_level,
                            VectorType         &dst,
                            const VectorType   &src) const;
 
+  /**
+   * Restrict a vector from level <tt>from_level</tt> to level
+   * <tt>from_level-1</tt> using the transpose operation of the @p prolongate
+   * method. If the region covered by cells on level <tt>from_level</tt> is
+   * smaller than that of level <tt>from_level-1</tt> (local refinement), then
+   * some degrees of freedom in <tt>dst</tt> are active and will not be
+   * altered. For the other degrees of freedom, the result of the restriction
+   * is added.
+   *
+   * @arg src is a vector with as many elements as there are degrees of
+   * freedom on the finer level involved.
+   *
+   * @arg dst has as many elements as there are degrees of freedom on the
+   * coarser level.
+   */
   virtual void restrict_and_add (const unsigned int from_level,
                                  VectorType         &dst,
                                  const VectorType   &src) const;