From: jzakiya <jzakiya@...>
Date: 2010-06-08T10:25:09+09:00
Subject: Re: Complex numbers contradiction?

On Jun 7, 6:59 pm, Andrew Duncan <andrew.dun...@sonos.com> wrote:
> As a mathematician, and compiler writer for the last twenty years or so,
> I am aware of that.
>
> Joel VanderWerf wrote:
> > Andrew Duncan wrote:
> >> But (as I now learn as I delve further into canonical Ruby syntax) it is
> >> a "feature" that 5/2 evaluates to 2 and not 2.5. So something of the
> >> sort is happening here.
>
> > Many languages, including C, do integer division that way.
>
> --
> Posted viahttp://www.ruby-forum.com/.

Using Ruby 1.8.7-p249 installed with rvm:

I get this:
-----------------------------------------
require 'complex'

Complex(1,1)**-1
=> Complex(0.5, -0.5)

1/Complex(1,1)
=> Complex(0, -1)
-----------------------------------------
But, when I use the 'mathn' lib I get:

require 'mathn'

Complex(1,1)**-1
=> Complex(1/2, -1/2)

1/Complex(1,1)
=> Complex(1/2, -1/2)
-----------------------------------------

So require the mathn library first for 1.8.7 to get correct results.

For 1.9.1 and 1.9.2 I also get correct results for both cases straight
out of the box.