Remove the Point.distance function and associated assertion. We only need the dot...

[spline3.git] / src / Point.hs

diff --git a/src/Point.hs b/src/Point.hs
index a92041e89845147f31af704f53613383c4244ee6..49ad534385846b57e60875849a0edff87c39653f 100644 (file)
--- a/src/Point.hs
+++ b/src/Point.hs
@@ -1,22 +1,17 @@
-{-# LANGUAGE TypeSynonymInstances #-}
+{-# LANGUAGE FlexibleInstances #-}
 
-module Point
+module Point (
+  Point,
+  dot,
+  scale
+  )
 where
 
-import Comparisons
+import Comparisons ((~=))
 
 
 type Point = (Double, Double, Double)
 
-x_coord :: Point -> Double
-x_coord (x, _, _) = x
-
-y_coord :: Point -> Double
-y_coord (_, y, _) = y
-
-z_coord :: Point -> Double
-z_coord (_, _, z) = z
-
 instance Num Point where
     (x1,y1,z1) + (x2,y2,z2) = (x1+x2, y1+y2, z1+z2)
     (x1,y1,z1) - (x2,y2,z2) = (x1-x2, y1-y2, z1-z2)
@@ -31,20 +26,7 @@ scale :: Point -> Double -> Point
 scale (x, y, z) d = (x*d, y*d, z*d)
 
 
--- | 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
+-- | Returns the dot product of two points (taken as three-vectors).
+dot :: Point -> Point -> Double
+dot (x1, y1, z1) (x2, y2, z2) =
+    (x2 - x1)^(2::Int) + (y2 - y1)^(2::Int) + (z2 - z1)^(2::Int)