Comments on: The Golden Ratio http://blog.jayway.com/2009/10/24/the-golden-ratio/ Sharing Experience Sun, 12 Feb 2012 05:23:29 +0000 hourly 1 http://wordpress.org/?v=3.3.1 By: Ulrik Sandberg http://blog.jayway.com/2009/10/24/the-golden-ratio/comment-page-1/#comment-15848 Ulrik Sandberg Sun, 15 Nov 2009 18:34:37 +0000 http://blog.jayway.com/?p=2139#comment-15848 I had expected some Scala wizards to criticize my feeble attempt at coding an algorithm in Scala, but it didn't happen. So I'll do it myself instead. What do I really want to do? If n is 1, the larger number should be divided by the smaller number. Otherwise, calculate the sum of the numbers and repeat on the larger number and the sum, for one less iteration. I'll start the interactive Scala shell and type this in: scala> def phi(a:Double, b:Double, n:Int): Double = n match { | case 1 => (a max b)/(a min b) | case _ => phi((a max b), a+b, n-1) | } phi: (Double,Double,Int)Double Testing it, and what do you know? It works: scala> phi(5., 8., 20) res1: Double = 1.618033988957902 I had expected some Scala wizards to criticize my feeble attempt at coding an algorithm in Scala, but it didn’t happen. So I’ll do it myself instead.

What do I really want to do? If n is 1, the larger number should be divided by the smaller number. Otherwise, calculate the sum of the numbers and repeat on the larger number and the sum, for one less iteration.

I’ll start the interactive Scala shell and type this in:

scala> def phi(a:Double, b:Double, n:Int): Double = n match {
| case 1 => (a max b)/(a min b)
| case _ => phi((a max b), a+b, n-1)
| }
phi: (Double,Double,Int)Double

Testing it, and what do you know? It works:

scala> phi(5., 8., 20)
res1: Double = 1.618033988957902

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