Re: [Boost-users] Looking for arithmetic metafunctions for ratios.

From: Andy Little (andy_at_[hidden])
Date: 2006-08-15 15:42:38

Hi Eric,

"Eric Lemings" <lemings_at_[hidden]> wrote in message 
news:D730FF7CEDDCA64483F9E99D999A158B41FC86_at_qxvcexch01.ad.quovadx.com...
Hi,

I'm looking for a metafunction like this:

template <
  class N1, class D1,
  class N2, class D2 >
struct times {
  typedef ... numer;
  typedef ... denom;
};

N1, D1, N2, and D2 are all MPL integral constant wrappers.  The numer
member of the times metafunction is the numerator N of the ratio
(preferably in reduced form) produced by (N1/D1) * (N2/D2) = (N/D).
Likewise, the denom member is the denominator D of the ratio produced
from this equation.

FWIW Quan http://sourceforge.net/projects/quan  has a rational type, you could 
use as a basis. there is also the mpl_math package in the boost vault, in 
Template Metaprogramming section I think

regards

Andy little