cpp-mathmatic-matrix/include/math/matrix/forward.h

#pragma once

#include <cstdlib>

namespace math::matrix {
template <typename T, std::size_t R, std::size_t C> class matrix;
}

namespace math::vector {
template <typename T, std::size_t N> class vector;
}

namespace math::matrix::concat_strategy {
struct {
} horizontal;
using horizontal_concat_t = decltype(horizontal);
struct {
} vertical;
using vertical_concat_t = decltype(vertical);
struct {
} diagonal;
using diagonal_concat_t = decltype(diagonal);
}