From: bbense+comp.lang.ruby.Dec.11.02@...
Date: 2002-12-12T04:20:46+09:00
Subject: Re: warnings -w

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In article <3DF5DC0A.8010106@spellmanhv.co.uk>,
Robert McGovern  <robertm@spellmanhv.co.uk> wrote:
>>>>>(2.4/0.2).to_i
>> 
>> D> => 11
>> 
>>  Float#to_i is the same than Float#truncate
>> 
>> pigeon% ruby -e 'p ((2.4/0.2).truncate)'
>> 11
>> pigeon% 
>> 
>> pigeon% ruby -e 'p ((2.4/0.2).floor)'
>> 11
>> pigeon% 
>> 
>> pigeon% ruby -e 'p ((2.4/0.2).ceil)'
>> 12
>> pigeon% 
>> 
>> pigeon% ruby -e 'p ((2.4/0.2).round)'
>> 12
>> pigeon% 
>
>As 2.4 /0.2 is fundementally 12, why should (2.4/0.2).floor or .truncate 
>give 11?

- - It's 12 on the real number line. It's something quite different
  in your computers implementation of IEEE floating point
  standards. 

>
>The method should be called on the result of the 2.4 / 0.2 calculation 
>which is 12 or 12.0 and therefore the result should always be 12.
>

- - This is a fact of life in doing floating point
  arithmetic on a computer and has absolutely nothing to do with
  Ruby. I suggest that you goggle IEEE floating point and learn
  some of the basics of floating point programming. 

- - Booker C. Bense 



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