-/* float norm(float x1, float y1, float x2, float y2) */
-/* { */
-/* float x = x2 - x1; */
-/* float y = y2 - y1; */
-/* return sqrt(x*x + y*y); */
-/* } */
+float xy_norm(float x1, float y1, float x2, float y2)
+{
+ float x = x2 - x1;
+ float y = y2 - y1;
+ return sqrt(x*x + y*y);
+}