diff -r cb26a6250401 -r da44ee225dad src/lemon/xy.h
--- a/src/lemon/xy.h	Sun Mar 06 21:20:49 2005 +0000
+++ b/src/lemon/xy.h	Mon Mar 07 07:53:20 2005 +0000
@@ -180,6 +180,29 @@
     return os;
   }
 
+  ///Rotate by 90 degrees
+
+  ///Returns its parameter rotated by 90 degrees in positive direction.
+  ///\relates xy
+  ///
+  template<typename T>
+  inline xy<T> rot90(const xy<T> &z)
+  {
+    return xy<T>(-z.y,z.x);
+  }
+
+  ///Rotate by 270 degrees
+
+  ///Returns its parameter rotated by 90 degrees in negative direction.
+  ///\relates xy
+  ///
+  template<typename T>
+  inline xy<T> rot270(const xy<T> &z)
+  {
+    return xy<T>(z.y,-z.x);
+  }
+
+  
 
   /// A class to calculate or store the bounding box of plainvectors.