All that because you can't overload between [4*4] and [3*3]

// File: matrix.hpp, created on Sep 8, 2011 by WeltEnSTurm


#ifndef MATRIX_HPP_
#define MATRIX_HPP_

template<typename T>
struct matrix3 {
    T
        x1, y1, z1,
        x2, y2, z2,
        x3, y3, z3;

    matrix3(const T* f){
        x1 = f[0], x2 = f[1], x3 = f[2];
        y1 = f[4], y2 = f[5], y3 = f[6];
        z1 = f[7], z2 = f[8], z3 = f[9];
    }
};

template<typename T>
struct matrix4 {
    T
        x1, y1, z1, w1,
        x2, y2, z2, w2,
        x3, y3, z3, w3,
        x4, y4, z4, w4;

    matrix4(const T* f){
        x1 = f[0],  y1 = f[1],  z1 = f[2],  w1 = f[3];
        x2 = f[4],  y2 = f[5],  z2 = f[6],  w2 = f[7];
        x3 = f[8],  y3 = f[9],  z3 = f[10], w3 = f[11];
        x4 = f[12], y4 = f[13], z4 = f[14], w4 = f[15];
    }
};

#endif /* MATRIX_HPP_ */