CoffeeScript Vector Math

vector.coffee

Number::toRadians = -> (@ * Math.PI) / 180
Number::toDegrees = -> (@ * 180) / Math.PI

Array::product = -> @reduce (a, e) -> a * e
Array::sum = -> @reduce (a, e) -> a + e

Array::zip = (args...) -> ((args...) ->
  longest = args.reduce ((a, b) -> (if a.length > b.length then a else b)), []
  longest.map (_, i) -> args.map (array) -> array[i])(@, args...)

#

class Vector
  constructor: (@x = 0, @y = 0, @z = 0) ->
  inspect: -> "#<Vector <#{@toArray().join ", "}>>"

  toArray: -> [@x, @y, @z]

  # returns boolean
  zero_p: -> @toArray().every (e) -> e is 0

  # returns scalar
  dot: (other) -> (@toArray().zip(other.toArray()).map (e) -> e.product()).sum()

  # returns scalar
  magnitude: -> Math.sqrt @dot @
  
  # returns angle measurement (radians)
  angleBetween: (other) -> Math.acos (@dot other) / (@magnitude() * other.magnitude())

alert (new Vector 1, 2, 3).angleBetween(new Vector 3, 4, 5).toDegrees()