Re: [boost] Compile-time power of a run-time base

From: Steven Watanabe (watanabesj_at_[hidden])
Date: 2008-02-02 16:48:39

AMDG

Bruno Lalande wrote:
> Hi Joaquin,
>
> Yes you're right, thanks for the advice. I really thought that an optimizing
> compiler was able to figure out this by itself, that is, transform things
> like n*n*n*n into (n*n)*(n*n). But a few tests shew me I was wrong.
>
> <snip>
> With your modification the function is finally much more than a syntactic
> helper since it runs faster than what an average programmer would type by
> hand. Shouldn't it be integrated somewhere into Boost ?
>   

There's such a function in Boost.Units.  It was originally needed 
because the
the result type depends on the exponent which must therefore be known at
compile time.

boost::units::quantity<boost::units::SI::area> area = 
boost::units::pow<2>(3.0 * boost::units::SI::meters);

Note that this is not in the trunk yet.

In Christ,
Steven Watanabe