1 files changed, 38 insertions, 5 deletions
diff --git a/lib/include/graph.hpp b/lib/include/graph.hpp
index c78fe9f..5ad4c8b 100644
--- a/lib/include/graph.hpp
+++ b/lib/include/graph.hpp
@@ -13,13 +13,44 @@
 
 #include "array_hash.hpp"
 
-class graph {
+class coordinate {
 public:
-  typedef struct coordinate {
-    double x;
-    double y;
-  } coordinate;
+  double x;
+  double y;
+
+  coordinate operator+(const coordinate& r) const {
+    coordinate rp = {0, 0};
+    rp.x = x + r.x;
+    rp.y = y + r.y;
+
+    return rp;
+  }
+
+  template <class T>
+  coordinate operator*(const T& a) const {
+    coordinate rp = *this;
+    rp.x *= a;
+    rp.y *= a;
+    return rp;
+  }
+
+  coordinate operator-(const coordinate& r) const {
+    coordinate rp = *this;
+    return rp + (r * -1);
+  }
+
+  coordinate operator-() const {
+    return *this * -1;
+  }
 
+  void operator+=(const coordinate& r) {
+    x += r.x;
+    y += r.y;
+  }
+};
+
+class graph {
+public:
   typedef struct vertex {
     coordinate r;
     std::vector<unsigned> nd;
@@ -49,4 +80,6 @@ public:
   graph const rotate();
 
   std::string write() const;
+
+  coordinate Δr(unsigned e) const;
 };