From 3f47781164a154c7266603072d8a24bfbb971d21 Mon Sep 17 00:00:00 2001
From: Bruno Blais <blais.bruno@gmail.com>
Date: Fri, 18 Nov 2022 16:14:15 -0500
Subject: [PATCH] Fianlize documentation

---
 include/deal.II/grid/grid_tools_cache.h | 17 ++++++++++++++---
 source/particles/particle_handler.cc    |  7 ++++---
 2 files changed, 18 insertions(+), 6 deletions(-)

diff --git a/include/deal.II/grid/grid_tools_cache.h b/include/deal.II/grid/grid_tools_cache.h
index 4d5ccfcf75..3b7e27fb30 100644
--- a/include/deal.II/grid/grid_tools_cache.h
+++ b/include/deal.II/grid/grid_tools_cache.h
@@ -169,11 +169,20 @@ namespace GridTools
     get_vertex_to_neighbor_subdomain() const;
 
     /**
-     * TODO
+     * Returns the std::map of std::vector of unsigned integer containing
+     * coinciding vertices labeled by an arbitrary element from them. This
+     * feature is used to identify cells which are connected by periodic
+     * boundaries.
      */
     const std::map<unsigned int, std::vector<unsigned int>> &
     get_coinciding_vertex_groups() const;
 
+    /**
+     * Returns the std::map of unsigned integer containing
+     * the label of a group of coinciding vertices. This
+     * feature is used to identify cells which are connected by periodic
+     * boundaries.
+     */
     const std::map<unsigned int, unsigned int> &
     get_vertex_to_coinciding_vertex_group() const;
 
@@ -303,14 +312,16 @@ namespace GridTools
 
     /**
      * Store an std::map of std::vector of unsigned integer containing
-     * coinciding vertices labeled by an arbitrary element from them
+     * coinciding vertices labeled by an arbitrary element from them.
      */
     mutable std::map<unsigned int, std::vector<unsigned int>>
       coinciding_vertex_groups;
 
     /**
      * Store an std::map of unsigned integer containing
-     * the label of a group of coinciding vertices
+     * the label of a group of coinciding vertices.
+     * This std::map is generally used in combination
+     * with the above std::map coinciding_vertex_groups.
      */
     mutable std::map<unsigned int, unsigned int>
       vertex_to_coinciding_vertex_group;
diff --git a/source/particles/particle_handler.cc b/source/particles/particle_handler.cc
index fae3bc91bd..a7d54914e9 100644
--- a/source/particles/particle_handler.cc
+++ b/source/particles/particle_handler.cc
@@ -1545,8 +1545,8 @@ namespace Particles
     // In the case of a parallel simulation with periodic boundary conditions
     // the vertices associated with periodic boundaries are not directly
     // connected to the ghost cells but they are connected to the ghost cells
-    // through their coinciding vertices. We loop over the coinciding vertices
-    // to identify cells in which ghost particles must be generated
+    // through their coinciding vertices. We gather the information about
+    // the coinciding vertices through the grid cache.
     const std::map<unsigned int, std::vector<unsigned int>>
       coinciding_vertex_groups =
         triangulation_cache->get_coinciding_vertex_groups();
@@ -1579,7 +1579,8 @@ namespace Particles
                 // looped over are contained inside the
                 // vertex_to_coinciding_vertex_group Consequently, we loop over
                 // the full content of the coinciding vertex group which will
-                // include the current vertex and we skip the current vertex.
+                // include the current vertex. When we reach the current vertex,
+                // we skip it to avoid repetition.
                 if (vertex_to_coinciding_vertex_group.find(cell->vertex_index(
                       v)) != vertex_to_coinciding_vertex_group.end())
                   {
-- 
2.39.5