calculus assignment bs

main.fs

(* Take a tree of expressions in and output the expression tree of the differentiation of it. (or something like that.)
   Copyright (c) 2012 darkf
   MIT license
*)

(* Assignment: http://pastebin.com/tiRVsxNx
   Graphs: http://f.imgtmp.com/FOVY7.jpg
*)

type Node =
  | Constant of int
  | Variable of string
  | Mult of Node * Node
  | Plus of Node * Node
  | Minus of Node * Node
  | Cos of Node
  | Sin of Node

(*let tree = Mult ((Variable "x"), Plus (
                                  (Plus ((Constant 2), (Variable "x")))
                                  ,
                                  (Cos
                                    (Minus ((Variable "x"), (Constant 4))))))*)

let tree = Mult (Constant 5, Variable "x")

let rec diff x = match x with
  | Plus(x,y) -> Plus (diff x, diff y)
  | Minus(x,y) -> Minus (diff x, diff y)
  | Mult(x,y) -> Plus(
                       Mult (diff x, y),
                       Mult (x, diff y)
                      )
  //| Cos(x) ->
  //| Sin(x) ->
  | Constant(x) -> Constant 0
  | Variable(x) -> Constant 1

printfn "%A" (diff tree)
System.Console.ReadKey(true) |> ignore