From: quixoticsycophant@... (Jeff Mitchell)
Date: 2004-05-13T15:58:51+09:00
Subject: Re: Major Addition Bug?

Mark Hubbart <discord@mac.com> wrote in message news:<528A9534-A443-11D8-ADAC-000502FDD5CC@mac.com>...
> On May 12, 2004, at 10:27 AM, Sean O'Dell wrote:
> 
> rather than rounding, you might consider:
> 
>    (625.91 + 900.00 + 22.00) - 1547.91 > 0.0000000001
>      ==>false
> 
> or even, for the scope of your app:
> 
>    class Float
>      def ==(other)
>        self - other < 0.000000000001
>      end
>    end
>      ==>nil
>    (625.91 + 900.00 + 22.00) == 1547.91
>      ==>true
> 
> or, if you aren't into redefing #==, you might just make a method, say, 
> #approx_eql?(other) for Float.
> 

Just a nitpick: this should be

class Float
   def ==(other)
      abs(self - other) < 0.000000000001
   end
end

Coming from a background in mathematics, I have personal
affection for:

class Float
   def within?(epsilon, other)
      abs(self - other) < epsilon
   end
end

EPSILON = 1e-8
# ...
if a.within?(EPSILON, b)
   # ...

I read this as, "if a is within epsilon of b" -- a common phrase
in analysis.