From: Michael Morin <uzimonkey@...>
Date: 2008-11-08T16:03:23+09:00
Subject: Re: what's easiest way to compare a Float & BigDecimal (i.e. like a equals mechanism)

Greg Hauptmann wrote:
> Hi,
> 
> what's easiest way to compare a Float & BigDecimal (i.e. like a equals
> mechanism)?  It seems that "==" does NOT work as they are different
> types.  Is there a way to do a comparison without having to convert
> types?
> 
> ?> a
> => #<BigDecimal:2395e98,'0.65E1',8(8)>
>>> x
> => 6.5
>>> a == x
> => false      #<<== DIDN'T WORK
> 
> tks
> 


It works fine for me.  If I do something like this:

f = 0.1
b = BigDecimal.new('0.1')
puts 'yes' if f == b

It will return true.  I've always stayed clear of the equality operator 
with floating point numbers.  Floating point cannot represent all 
numbers exactly, so comparing it with something like a BigDecimal (which 
can represent all numbers exactly) might be problematic.