add to documentation of get_coarse_mesh_description()

diff --git a/include/deal.II/grid/grid_tools.h b/include/deal.II/grid/grid_tools.h
index 9a6e085ddd2e4a560a3ab0935d7304cba1505fd8..321ea99a63902ca67b598794db50b18094a83fe5 100644 (file)
--- a/include/deal.II/grid/grid_tools.h
+++ b/include/deal.II/grid/grid_tools.h
@@ -276,6 +276,10 @@ namespace GridTools
    * Return the arrays that define the coarse mesh of a Triangulation. This
    * function is the inverse of Triangulation::create_triangulation().
    *
+   * The return value is a tuple with the vector of vertices, the vector of
+   * cells, and a SubCellData structure. The latter contains additional
+   * information about faces and lines.
+   *
    * This function is useful in cases where one needs to deconstruct a
    * Triangulation or manipulate the numbering of the vertices in some way: an
    * example is GridGenerator::merge_triangulations().