Scala/sqrt/sqrt.scala


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object Main extends App {

  def abs(x:Double) = if (x < 0) -x else x

  def sqrt(x: Double) = {

    def sqrtIter(guess: Double): Double =
      if (isGoodEnough(guess)) guess
      else sqrtIter(improve(guess))

    def isGoodEnough(guess: Double) =
      abs(guess * guess - x ) /x < 0.001

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

    sqrtIter(1.0)
  }

  println(sqrt(2))
  println(sqrt(0.001))
  println(sqrt(0.1e-20))
  println(sqrt(1.0e20))
  println(sqrt(1.0e50))

}