From: bug@...
Date: 2008-02-10T04:15:02+09:00
Subject: Re: Internal Rate of Return (#156)

On Feb 9, 5:48 am, Alex Shulgin <alex.shul...@gmail.com> wrote:
> On Feb 8, 4:01 pm, Ruby Quiz <ja...@grayproductions.net> wrote:
>
>
>
> > Keep in mind that an IRR greater than 100% is possible. Extra credit if you can
> > also correctly handle input that produces negative rates, disregarding the fact
> > that they make no sense.
>
> Can we return 1/0.0 if NPV does not evaluate to 0 for a reasonably
> large IRR?
>
> irr([+100,+10,+10,+10])
> => Infinity
>
> Many thanks to James for your great job as the Quizmaster! :-)
> --
> Alex

Such cases have an undefined IRR, and thus the behavior is undefined.

Harrison Reiser