----Original Message---- From: boost-bounces@lists.boost.org [mailto:boost-bounces@lists.boost.org] On Behalf Of John Maddock Sent: 05 February 2008 10:26 To: boost@lists.boost.org Subject: Re: [boost] [Boost] Compile-time power of a run-time base
Bruno Lalande wrote:
* The result type is not necessarily going to be the same as the arguments so it would need to use Boost.Typeof or some such.
Yep, I had already thought about this improvement.
The only use case I can think of is where the argument is an integer rather than a real number (and the result is therefore a double),
boost.units: pow<3>( length ) is going to have units of volume.
* Rational exponents need to work, so I would need a way to specialize the function to work with boost::units::static_rational. I would expect the customization
I'm a bit concerned about this interface: my guess is that 90% or more of users would just want integer exponents, and these should be very easy to use, preferably simply:
pow<2>(val)
Hmmm, I wonder if we can define an overload such that:
pow<2,3>(val)
is also valid?
... and I /believe/ that boost.units only needs half powers. So (modulu units) template<class T1, class T2, int N> T2 pow<N,2>(T1 val) { return sqrt(pow<N>(val)); } should do it. ... in fact, I suspect that boost.math pow should /only/ offer the integral powers, and boost.units should wrap it to add the rational support. -- Martin Bonner Senior Software Engineer/Team Leader PI SHURLOK LTD Telephone: +44 1223 441434 / 203894 (direct) Fax: +44 1223 203999 Email: martin.bonner@pi-shurlok.com www.pi-shurlok.com disclaimer