taylor.elm

import List exposing (sum, map, foldl)

pow : Float -> Float -> Float
pow num p =
  if p == 0 then
    1
  else if p > 0 then
    num * (pow num (p - 1))
  else
    1 / num * (pow num (p + 1))

fact : Float -> Float
fact x = if x <= 0 then 1 else x * fact(x - 1)

sine : Float -> Float
sine x =
  sum (map (\i -> (pow -1 i) * (pow x (i * 2 + 1)) / (fact (i * 2 + 1))) [0..9])

sinefold : Float -> Float
sinefold x =
  foldl (\i sum -> sum + (pow -1 i) * (pow x (i * 2 + 1)) / (fact (i * 2 + 1))) 0 [0..9]