From: Jacob Fugal <lukfugl@...>
Date: 2005-12-24T04:51:17+09:00
Subject: Re: Why not Python? (No, no, I am not a spy)

On 12/23/05, Jeff Wood <jeff.darklight@gmail.com> wrote:
> # complete recursive:
>
> def factorial( x )
>   return 0 if x < 1
>   x * factorial( x - 1 )
> end
>
> # tail-recursive:
>
> def factorial( x, sum = 1 )
>   return 0 if x < 1
>   factorial( ( x - 1 ), ( sum * x ) )
> end
>
> # iterative:
>
> def factorial( x )
>   sum = 1
>   for i in (1..x).to_a
>     sum *= i
>   end
> end

With bugfixes:

  # complete recursive:
  def factorial( x )
    return 1 if x < 1
    x * factorial( x - 1 )
  end

  # tail-recursive:
  def factorial( x, sum = 1 )
    return sum if x < 1
    factorial( ( x - 1 ), ( sum * x ) )
  end

  # iterative:
  def factorial( x )
    sum = 1
    for i in (1..x).to_a
      sum *= i
    end
    sum
  end

:)

Jacob Fugal