paradiso/src/lib/matrixbase.hpp

#ifndef PARADISO_MATRIXBASE_HPP
#define PARADISO_MATRIXBASE_HPP

#include <cmath>
#include <numeric>

namespace paradiso {

template <typename Scalar, typename Derived> struct MatrixBase {

    using value_type = Scalar;
    using reference = Scalar&;
    using const_reference = const Scalar&;
    using pointer = Scalar*;
    using const_pointer = const Scalar*;
    using iterator = Scalar*;
    using const_iterator = const Scalar*;

    constexpr pointer data() { return &derived().data[0]; }
    constexpr const_pointer data() const noexcept { return &derived().data[0]; }

    constexpr iterator begin() noexcept { return this->data(); }
    constexpr iterator end() noexcept { return this->data() + size(); }
    constexpr const_iterator begin() const noexcept { return this->data(); }
    constexpr const_iterator end() const noexcept { return this->data() + size(); }
    constexpr const_iterator cbegin() const noexcept { return this->data(); }
    constexpr const_iterator cend() const noexcept { return this->data() + size(); }

    constexpr Scalar& operator[](std::size_t i) { return this->data()[i]; }
    constexpr const Scalar& operator[](std::size_t i) const {
        return this->data()[i];
    }

    Derived& derived() { return static_cast<Derived&>(*this); }
    const Derived& derived() const {
        return static_cast<const Derived&>(*this);
    }

    std::size_t size() const {
        return std::extent<decltype(Derived::data)>::value;
    }

    constexpr Derived& fill(const Scalar& v) noexcept {
        std::fill(std::begin(*this), std::end(*this), Scalar(v));
        return derived();
    }

    static constexpr Derived zero() noexcept {
        Derived d;
        d.fill(0);
        return d;
    }

    constexpr Scalar squared_norm() const { return dot(*this, *this); }

    constexpr Scalar norm() const { return std::sqrt(squared_norm()); }

    constexpr Derived normalized() const { return *this / this->norm(); }

    constexpr void normalize() { *this /= this->norm(); }

    static constexpr Scalar dot(const Derived& a, const Derived& b) {
        return std::inner_product(std::begin(a), std::end(a), std::begin(b),
                                  Scalar{0});
    }

    static constexpr Derived lerp(const Derived& a, const Derived& b,
                                  const Scalar& t) {
        return a + (b - a) * t;
    }

    constexpr void operator*=(const Scalar& b) {
        for (auto& e : *this)
            e *= b;
    }
    constexpr void operator/=(const Scalar& b) {
        for (auto& e : *this)
            e /= b;
    }
    constexpr void operator+=(const Scalar& b) {
        for (auto& e : *this)
            e += b;
    }
    constexpr void operator-=(const Scalar& b) {
        for (auto& e : *this)
            e -= b;
    }

    constexpr const Derived operator*(const Scalar& b) const {
        Derived r(derived());
        for (auto& e : r)
            e *= b;
        return r;
    }
    constexpr const Derived operator/(const Scalar& b) const {
        Derived r(derived());
        for (auto& e : r)
            e /= b;
        return r;
    }
    constexpr const Derived operator+(const Scalar& b) const {
        Derived r(derived());
        for (auto& e : r)
            e += b;
        return r;
    }
    constexpr const Derived operator-(const Scalar& b) const {
        Derived r(derived());
        for (auto& e : r)
            e -= b;
        return r;
    }
};

} // namespace paradiso
#endif