// Square root, first version (Chapter 4, Scala by Example)

def abs(x: Double) = if (x > 0.0) x else -x

def square(x: Double) = x * x

def improve(guess: Double, x: Double): Double =  (guess + x / guess) / 2

def isGoodEnough(guess: Double, x: Double): Boolean = abs( square(guess) - x) < 0.001

def sqrtIter(guess: Double, x: Double): Double = { 
  println( guess )
  if ( isGoodEnough(guess, x)) guess
  else sqrtIter(improve(guess, x), x)
}


def sqrt(x: Double) = sqrtIter(1.0, x)