Andy Little wrote:
You must've missed this: Dan wrote me an email a while back. He says: "Interestingly using fusion::fold to do maths on boost::arrays, I'm finding that with vc8.0 fusion significantly outperforms the standard library equivalent code, presumably as it has more information available at compile time, and with inlining it effectively unrolls the entire loops."
I asked Dan to add his tests to libs/fusion/example to showcase this favorable "phenomena" :-).
I can't find that, but I am probably looking in the wrong place. Do you mean Boost CVS?
Sorry, you'll have to wait a bit more. Dan says he'll do it over the weekend.
BTW. By using a tuple rather than an array, then you can use representing zero and one. IOW zero<T> one<T> .
hence:
template <typename TL, typename TR> zero<typeof(TL() * TR() )> operator *( Tl , zero<TR>) { return zero<typeof(TL() * TR() )>(); } It should be relatively simple for the compiler to optimise such calcs away. Very useful for matrix calcs. (originally suggested by Geoffrey Irving).
Indeed. Also, with Fusion, you have the option to use purely constant sequences such as mpl::vector_c together with plain sequences, or even user defined sequences and adapted/converted structs/classes. Regards, -- Joel de Guzman http://www.boost-consulting.com http://spirit.sf.net