src/Point.hs

   1 {-# LANGUAGE FlexibleInstances #-}
   2
   3 module Point (
   4   Point,
   5   dot,
   6   scale
   7   )
   8 where
   9
  10 type Point = (Double, Double, Double)
  11
  12 instance Num Point where
  13     (x1,y1,z1) + (x2,y2,z2) = (x1+x2, y1+y2, z1+z2)
  14     (x1,y1,z1) - (x2,y2,z2) = (x1-x2, y1-y2, z1-z2)
  15     (x1,y1,z1) * (x2,y2,z2) = (x1*x2, y1*y2, z1*z2)
  16     abs (x, y, z) = (abs x, abs y, abs z)
  17     signum (x, y, z) = (signum x, signum y, signum z)
  18     fromInteger n = (fromInteger n, fromInteger n, fromInteger n)
  19
  20
  21 -- | Scale a point by a constant.
  22 scale :: Point -> Double -> Point
  23 scale (x, y, z) d = (x*d, y*d, z*d)
  24
  25
  26 -- | Returns the dot product of two points (taken as three-vectors).
  27 {-# INLINE dot #-}
  28 dot :: Point -> Point -> Double
  29 dot (x1, y1, z1) (x2, y2, z2) =
  30     (x2 - x1)^(2::Int) + (y2 - y1)^(2::Int) + (z2 - z1)^(2::Int)