[boost] [fusion] matrix?

5 Sep 2006

      Hi Boosters,

Is it possible to use fusion to do a compile time matrix?

The code below uses boost::tuple, but presumably fusion could do this stuff 
better?
Things that might be useful include get column N, get cofactor<R,C> etc, etc.

Might be an interesting example for fusion, but I don't know ...

Its kind of fun anyway.

regards
Andy Little

---------------------

#include <quan/out/time.hpp>
#include <quan/out/reciprocal_time.hpp>
#include <boost/tuple/tuple.hpp>

template <int Rows, int Columns,typename TupleSequence>
struct rc_matrix{
    TupleSequence seq;
    // 0 based
    template <int Row, int Column>
    typename boost::tuples::element<
        Columns * Row + Column,TupleSequence
    >::type
    at() const
    {
        return seq.get<Columns * Row + Column>();
    }
    rc_matrix( TupleSequence const & s): seq(s){}
};

#include <iostream>
int main()
{
    typedef boost::tuples::tuple<
        double,quan::reciprocal_time::per_s,
        quan::time::s,double
    > matrix_elements;
    rc_matrix<
        2,2,
        matrix_elements
    > 
mat(matrix_elements(2.,quan::reciprocal_time::per_s(3),quan::time::s(8),4.));
    std::cout << mat.at<0,0>() << '\n';
    std::cout << mat.at<0,1>() << '\n';
    std::cout << mat.at<1,0>() << '\n';
    std::cout << mat.at<1,1>() << '\n';

    std::cout << mat.at<0,1>() * mat.at<1,0>() <<'\n';

}