+
+
+-- | Returns the distance between p1 and p2.
+distance :: Point -> Point -> Double
+distance p1 p2 =
+ sqrt $ (x2 - x1)^(2::Int) + (y2 - y1)^(2::Int) + (z2 - z1)^(2::Int)
+ where
+ x1 = x_coord p1
+ x2 = x_coord p2
+ y1 = y_coord p1
+ y2 = y_coord p2
+ z1 = z_coord p1
+ z2 = z_coord p2
+
+
+-- | Returns 'True' if p1 is close to (within 'epsilon' of) p2,
+-- 'False' otherwise.
+is_close :: Point -> Point -> Bool
+is_close p1 p2 = (distance p1 p2) ~= 0