code logical error in SML

Question

I'm using the below code for square root from a cornell course, however the code returns wrong values, The code is

fun squareRoot(x: real): real =
  let
    val delta = 0.0001
    fun goodEnough(guess: real): bool =
      if(abs(guess*guess - x) < delta) then true else false
    fun improve(guess: real): real =
      (guess + x/guess) / 2.0
    fun tryGuess(guess: real): real =
      if goodEnough(guess) then guess
      else tryGuess(improve(guess))
  in
    tryGuess(1.0)
  end

When executing

 use "squareroot1.sml";
[opening squareroot1.sml]
val squareRoot = fn : real -> real
val it = () : unit
- squareroot 9.0;
val it = 1.0 : real
-

It always returns 1.0 as the root can you please tell why this is happening?

I get `val it = 3.0000000014 : real` with that code. Did you forget to save, or load the wrong file? — molbdnilo, Oct 31 '13 at 12:33
Nope same file.....is something wrong with my SMLNJ installation? — user2433145, Nov 01 '13 at 13:58
Try to enter the code directly into the interpreter instead of using "use" and see if that works. — molbdnilo, Nov 01 '13 at 19:17

score 0 · Answer 1 · answered Nov 07 '13 at 03:18

0

There's a typo when you call the function, you need to change the squareroot to squareRoot.

answered Nov 07 '13 at 03:18

SunsetRider

96
3

code logical error in SML

1 Answers1