From 472073c22b9c4b739fd047cba1f94537889c5e27 Mon Sep 17 00:00:00 2001
From: Joachim Schoeberl <joachim.schoeberl@tuwien.ac.at>
Date: Sun, 21 May 2023 14:35:09 +0200
Subject: [PATCH] counting num vertices in parallel

---
 libsrc/core/array.hpp        |  4 ++--
 libsrc/meshing/meshclass.cpp | 22 +++++++++++++++++++++-
 2 files changed, 23 insertions(+), 3 deletions(-)

diff --git a/libsrc/core/array.hpp b/libsrc/core/array.hpp
index 7414db78..170f51b8 100644
--- a/libsrc/core/array.hpp
+++ b/libsrc/core/array.hpp
@@ -628,7 +628,7 @@ namespace ngcore
   FlatArray<T> View (FlatArray<T> fa) { return fa; }
 
   template <typename T, typename TI>
-  auto Max (FlatArray<T,TI> array, T max = std::numeric_limits<T>::min()) -> T
+  auto Max (FlatArray<T,TI> array, typename std::remove_const<T>::type max = std::numeric_limits<T>::min()) -> T
   {
     for (auto & v : array)
       if (v > max) max = v;
@@ -636,7 +636,7 @@ namespace ngcore
   }
 
   template <typename T, typename TI>
-  auto Min (FlatArray<T,TI> array, T min = std::numeric_limits<T>::max()) -> T
+  auto Min (FlatArray<T,TI> array, typename std::remove_const<T>::type min = std::numeric_limits<T>::max()) -> T
   {
     for (auto & v : array)
       if (v < min) min = v;
diff --git a/libsrc/meshing/meshclass.cpp b/libsrc/meshing/meshclass.cpp
index 9f230ac9..a5595b23 100644
--- a/libsrc/meshing/meshclass.cpp
+++ b/libsrc/meshing/meshclass.cpp
@@ -6810,8 +6810,9 @@ namespace netgen
 
   void Mesh :: ComputeNVertices ()
   {
-    numvertices = 0;
 
+    numvertices = 0;
+    /*
     for (const Element & el : VolumeElements())
       for (PointIndex v : el.Vertices())
         if (v > numvertices) numvertices = v;
@@ -6821,6 +6822,25 @@ namespace netgen
         if (v > numvertices) numvertices = v;
 
     numvertices += 1-PointIndex::BASE;
+    */
+    numvertices = 0;    
+    numvertices =
+      ParallelReduce (VolumeElements().Size(),
+                      [&](size_t nr)
+                      {
+                        return int(Max(VolumeElements()[nr].Vertices()));
+                      },
+                      [](auto a, auto b) { return a > b ?  a : b; },
+                      numvertices);
+    numvertices =
+      ParallelReduce (SurfaceElements().Size(),
+                      [&](size_t nr)
+                      {
+                        return int(Max(SurfaceElements()[nr].Vertices()));
+                      },
+                      [](auto a, auto b) { return a > b ?  a : b; },
+                      numvertices);
+    numvertices += 1-PointIndex::BASE;    
   }
 
   int Mesh :: GetNV () const