From: Markus <markus@...>
Date: 2004-10-15T23:57:34+09:00
Subject: Re: Rounding to X digits

     Interesting.   I hope to heck you used a script to find that edge
case.  What made you suspect there would be a difference, given that
they are mathematically equivalent?  

     I'll definitely come back to this after the coffee hits.

     -- Markus


On Fri, 2004-10-15 at 07:28, trans. (T. Onoma) wrote:
> On Thursday 14 October 2004 01:55 pm, Markus wrote:
> | Here's mine (with a few extras):
> |
> | class Numeric
> |     def iff(cond)
> |         cond ? self : self-self
> |         end
> |     def to_the_nearest(n)
> |         n*(self/n).round
> |         end
> |     def aprox(x,n=0.001)
> |         (to_the_nearest n) == (x.to_the_nearest n)
> |         end
> |     def at_least(x); (self >= x) ? self : x; end
> |     def at_most(x);  (self <= x) ? self : x; end
> |     end
> |
> 
> |     def to_the_nearest(n)
> |         n*(self/n).round
> |         end
>   def round_to_nearest( n=0.01 )
>     (self * (1/n)).round.to_f / (1/n)
>   end
> 
> For some reason they don't give the exact same answer. Try an edge case.
> 
>   irb(main):066:0> 0.1 * (134.45/0.1).round
>   => 134.4
>   irb(main):067:0> (134.45 * (1/0.1)).round.to_f / (1/0.1)
>   => 134.5
> 
> T.