From: Rick DeNatale <rick.denatale@...>
Date: 2008-09-15T00:30:49+09:00
Subject: Re: how do deal with huge numbers and keep them accurate?

------=_Part_89585_1128978.1221406667510
Content-Type: text/plain; charset=ISO-8859-1
Content-Transfer-Encoding: 7bit
Content-Disposition: inline

On Sun, Sep 14, 2008 at 10:24 AM, Axel Etzold <AEtzold@gmx.de> wrote:

>
>
> > odd=1231231
> > result=410410.333333333
> >
> > odd=123123123123121    (15 digits)
> > result=41041041041040.3
> >
> > so far so good,now:
> > odd=1231231231231231   (16 digits)
> > result=4.1041041041041e+014     (given with no remainder)
> >    [It's a wrong answer! the result should have been  ---
> > 410410410410410.33333]
> >
> > What do i need to chance in the code to make it happen?
> > in the future i should deal with larger numbers and the accuracy is
> > essential.
> >
> > thanks in advanced, tomi.
> > --
> > Posted via http://www.ruby-forum.com/.
>
> Dear Tomi,
>
> in addition to Rick's post, I#d like to say that in Ruby, you can easily
> calculate correctly with fractions, using
> the built-in Rational class:
>
>
Yes, I should have pointed out that even

1231231 / 3 => 410410.333333333

Isn't really the 'correct answer'.  Since the correct answer has an infinite
number of 3's after the decimail point.

A big decimal is still a float, albeit a float with lots of digits and in
decimal rather than binary, but it still has the characteristics of a float,
there are an infinite number of numbers which can't be exactly represented.

Of course neither Floats nor Rationals can represent irrational numbers
exactly.

-- 
Rick DeNatale

My blog on Ruby
http://talklikeaduck.denhaven2.com/

------=_Part_89585_1128978.1221406667510--