From: Michael Ulm <michael.ulm@...>
Date: 2007-09-04T20:10:34+09:00
Subject: Re: 0.06 == 0.06 returns false in Ruby?

Pe�a wrote:
> From: Michael Ulm [mailto:michael.ulm@isis-papyrus.com] 
> # Daniel Berger wrote:
> # > class Float
> # >    def ==(other)
> # >       self.to_s == other.to_s
> # >    end
> # > end
> # Oh yes, nice one. This fulfills 
> # 'from  x==y and y==z follows x==z'
> # Unfortunately it does not fulfill some other properties one
> 
> w a little help fr bigdecimal, a little goes a long long way
> 
>> class Float
>>   def to_dec
>>      BigDecimal.new(self.to_s)
>>   end
>> end
> => nil
>> class Fixnum
>>    def to_dec
>>       BigDecimal.new(self.to_s)
>>    end
>> end
> => nil
> 
>> x=0.06.to_dec
>> y=0.05.to_dec + 0.01.to_dec
>> x==y
> => true
>> z=0.02.to_dec+0.04.to_dec
>> y==z
> => true
>> z==y
> => true
>> x==z
> => true
>> z==x
> => true
--snip--

However (among other problems):

> x = (1.0/3.0).to_dec
> y = 1.0.to_dec / 3.0.to_dec
> x == y # => false

HTH,

Michael