From: Rene Gassmoeller <rene.gassmoeller@mailbox.org>
Date: Mon, 21 May 2018 18:38:01 +0000 (-0700)
Subject: Update documentation
X-Git-Tag: v9.1.0-rc1~1114^2~1
X-Git-Url: https://gitweb.dealii.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=bacba12f0c60f75084d3203c0ec21c64e9631c3f;p=dealii.git

Update documentation
---

diff --git a/include/deal.II/grid/grid_tools.h b/include/deal.II/grid/grid_tools.h
index b5df22b7cb..17d0d10237 100644
--- a/include/deal.II/grid/grid_tools.h
+++ b/include/deal.II/grid/grid_tools.h
@@ -770,9 +770,15 @@ namespace GridTools
    * and querying for each cell where its vertices are through the (optional)
    * `mapping` argument.
    *
-   * The size of the returned map equals Triangulation::n_used_vertices(),
-   * (not Triangulation::n_vertices()). If you use the default `mapping`, the
-   * returned map satisfies the following equality:
+   * In serial and parallel::shared triangulations the size of the returned map
+   * equals Triangulation::n_used_vertices(), (not Triangulation::n_vertices()).
+   * Note that in parallel::distributed triangulations only vertices in locally
+   * owned cells and ghost cells are returned, as for all other vertices their
+   * real location might not be known (e.g. for distributed computations using
+   * MappingQEulerian).
+   *
+   * If you use the default `mapping`, the returned map satisfies the following
+   * equality:
    *
    * @code
    * used_vertices = extract_used_vertices(tria);