From: Bertram Scharpf <lists@...>
Date: 2009-09-26T07:14:56+09:00
Subject: Re: Ruby Noob issue

Hi,

Am Freitag, 25. Sep 2009, 10:17:53 +0900 schrieb Fred Ige:
> Satish Talim wrote:
> > Fred, (5/9) is integer division. The decimal part is truncated leaving 
> > you
> > with 0. Use (5.0/9) instead.
> > Satish
> 
> Thanks! It works now
> I cant believe such a small issue throw me off for so long.

Actually, you're not the first one to stumble over the
integer/floating point problem.

As expressions are evaluated from left to right, the first number
coerces the value to be Float. You could also say:

  (x.to_f - 32) * 5 / 9

Or

  class Numeric
    def f2c
      (to_f - 32) * 5 / 9
    end
  end

  -32.f2c  #=> 0.0


Here's another pitfall about floating point values. Be aware that
aren't exact in general.

  "%20.18f" % 0.3       #=> "0.299999999999999989"

Bertram


-- 
Bertram Scharpf
Stuttgart, Deutschland/Germany
http://www.bertram-scharpf.de