From: Elias Athanasopoulos <elathan@...>
Date: 2004-05-06T16:17:17+09:00
Subject: Re: 0.0 sign

On Thu, May 06, 2004 at 04:28:36AM +0900, Mark Hubbart wrote:
> 
> On May 5, 2004, at 10:33 AM, Elias Athanasopoulos wrote:
> 
> >Hello!
> >
> >I don't know if this is intentional, but is there a reason
> >that 0.0 holds the sign?
> 
> IEEE 754 (floating point arithmetic standard) specifies negative zero 
> for floats. For more explanation, see
> http://www.obtuse.com/resources/negative_zero.html
> 
> if a mathematical result too small for your hardware to compute is 
> returned, you can determine whether it was on the negative side, or the 
> positive side.
> 
>   def really_complex_function(num)
>     num/1_000_000_000_000_000_000.0
>   end
>     ==>nil
>   really_complex_function(  0.000_000_000_000_000_000_1 )
>     ==>0.0
>   really_complex_function( -0.000_000_000_000_000_000_1 )
>    ==>-0.0

Yes, but how can you distinguish them *inside* your code? Since
0.0 == -0.0, 0.0 === -0.0 and even 0.0.eql?(-0.0) is true.

Regards,
-- 
University of Athens			I bet the human brain 
Physics Department				is a kludge --Marvin Minsky