minkowski_distance.h

// Description: Minkowski distance
// Documentation: distances.txt

#ifndef PASTELMATH_MINKOWSKI_DISTANCE_H
#define PASTELMATH_MINKOWSKI_DISTANCE_H

#include "pastel/sys/mytypes.h"
#include "pastel/math/distance/distance_concept.h"
#include "pastel/math/distance/distance_base.h"
#include "pastel/sys/math/powers.h"

#include <cmath>

namespace Pastel
{

    template <typename Real>
    class Minkowski_Distance
    : public DistanceBase<Minkowski_Distance<Real>, Real>
    {
    public:
        using Real_ = Real;

        explicit Minkowski_Distance(const Real& distance = 0, const Real& p = 2)
        : distance_(std::pow(distance, p))
        , p_(p)
        {}

        Minkowski_Distance(Distance_Native, const Real& distance, const Real& p = 2)
        : distance_(abs(distance))
        , p_(p)
        {}

        Minkowski_Distance(const Minkowski_Distance&) = default;
        Minkowski_Distance(Minkowski_Distance&&) = default;
        Minkowski_Distance& operator=(const Minkowski_Distance&) = default;

        explicit operator Real() const {
            using std::pow;
            return pow(distance_, inverse(p_));
        }

        const Real& operator~() const {
            return distance_;
        }

        decltype(auto) replace(integer axis, const Real& from, const Real& to) {
            distance_ += std::pow(abs(to), p_) - std::pow(abs(from), p_);
            return *this;
        }

        decltype(auto) operator*=(const Real& amount) {
            distance_ *= std::pow(abs(amount), p_);
            return *this;
        }

    private:
        Real distance_;
        Real p_;
    };

}

#endif