From ff4ec3c5f56939a75ab6cf00ae519ed80abaacee Mon Sep 17 00:00:00 2001
From: Mathieu Dutour Sikiric <mathieu.dutour@gmail.com>
Date: Mon, 25 Dec 2023 13:31:05 +0100
Subject: [PATCH] Add function IsSymmetricGraph to the GraphicalFunctions.h

---
 src_graph/GRAPH_GraphicalFunctions.h | 19 +++++++++++++++++++
 1 file changed, 19 insertions(+)

diff --git a/src_graph/GRAPH_GraphicalFunctions.h b/src_graph/GRAPH_GraphicalFunctions.h
index eff94a2..ce94242 100644
--- a/src_graph/GRAPH_GraphicalFunctions.h
+++ b/src_graph/GRAPH_GraphicalFunctions.h
@@ -291,6 +291,25 @@ template <typename Tgr> bool IsSimpleGraph(Tgr const &GR) {
   return true;
 }
 
+template <typename Tgr> bool IsSymmetricGraph(Tgr const &GR) {
+  size_t nbVert = GR.GetNbVert();
+  MyMatrix<int8_t> M=ZeroMatrix<int8_t>(nbVert,nbVert);
+  for (size_t iVert = 0; iVert < nbVert; iVert++) {
+    std::vector<size_t> LAdj = GR.Adjacency(iVert);
+    for (auto & eAdj : LAdj) {
+      M(iVert, eAdj) = 1;
+    }
+  }
+  for (size_t iVert=0; iVert<nbVert; iVert++) {
+    for (size_t jVert=iVert+1; jVert<nbVert; jVert++) {
+      if (M(iVert, jVert) != M(jVert, iVert)) {
+        return false;
+      }
+    }
+  }
+  return true;
+}
+
 template <typename Tgr>
 std::vector<std::vector<size_t>> GetEdgeSet(Tgr const &GR) {
   size_t nbVert = GR.GetNbVert();