From: "Berger, Daniel" <djberge@...>
Date: 2002-05-31T02:59:12+09:00
Subject: RE: Infinity (?!)



> -----Original Message-----
> From: wconrad@yagni.com [mailto:wconrad@yagni.com]
> Sent: Thursday, May 30, 2002 12:57 PM
> To: ruby-talk@ruby-lang.org
> Subject: Re: Infinity (?!)
> 
> 
> On Thu, May 30, 2002 at 11:04:30PM +0900, Sean Russell wrote:
> > Dossy wrote:
> > 
> > > Float allowing division by zero is certainly not of least surprise
> > > to me.  ;-)
> > 
> > Yeah, I think it is sort of silly, too.  From what I 
> remember of my math, 
> > dividing by zero is "illegal".
> 
> True, but the math we do with floats bears only a passing resemblance
> to the math we learned in our youth (floats are not reals, no matter
> what Wirth says).  Nor is it too odd to define 1 / 0 as infinity --
> infinity is a just as reasonable a result as "you can't do that,"
> considering that 1 / n approaches infinity as n approaches 0.
> 
> Computer math is a little surprising.
> 
> > However, IEEE 754 (Institute of Electrical and Electronics 
> Engineers. IEEE 
> > Standard for Binary Floating-Point Arithmetic. ANSI/IEEE 
> Std 754-1985.) 
> > defines rules for operations such as this, and it specifies 
> that n/0 -> 
> > Infinity, -n/0 -> -Infinity, and 0/0 -> NaN.  Because of 
> this, I'm a little 
> > surprised that Integer math in Ruby doesn't follow the same rules.
> 
> I'd be very surprised to find IEEE 754 applied to integers.  Integers
> are quite different animals.
> 
>         Wayne Conrad
>

That's what I like about standards - there are so many to choose from. ;-P

Dan