m2l_indices.hpp

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#ifndef NIHU_M2L_INDICES_HPP_INCLUDED
#define NIHU_M2L_INDICES_HPP_INCLUDED
 
#include "bounding_box.hpp"
 
#include <type_traits>
 
namespace NiHu
{
namespace fmm
{
template <unsigned Dim>
class m2l_indices
{
public:
    static size_t const dimension = Dim;
    typedef bounding_box<dimension> bounding_box_t;
    typedef typename bounding_box_t::location_t location_t;
 
private:
    static size_t drel2idx(location_t const &drel, std::integral_constant<size_t, 1U>)
    {
        return size_t(round(drel(0)) + 3);
    }
 
    static size_t drel2idx(location_t const &drel, std::integral_constant<size_t, 2U>)
    {
        return size_t(round(drel(0)) + 3 + 7 * (round(drel(1)) + 3));
    }
 
    static size_t drel2idx(location_t const &drel, std::integral_constant<size_t, 3U>)
    {
        return size_t(round(drel(0)) + 3 + 7 * (round(drel(1)) + 3) + 7 * 7 * (round(drel(2)) + 3));
    }
public:
 
    static size_t eval(bounding_box_t const &to, bounding_box_t const &from)
    {
        location_t drel = (to.get_center() - from.get_center()) / to.get_diameter();
        return drel2idx(drel, std::integral_constant<size_t, dimension>());
    }
};
} // end of namespace fmm
} // namespace NiHu
 
#endif /* NIHU_M2L_INDICES_HPP_INCLUDED */