#ifndef VEC_3
#define VEC_3

#include <cmath>
#include <iostream>

class vec3{
  public:
    double e[3];

    vec3() : e{0, 0, 0} {}
    vec3(double e0, double e1, double e2) : e{e0, e1, e2} {}

    double x() const;
    double y() const;
    double z() const;

    vec3 operator-() const;
    double operator[](int i) const;
    double &operator[](int i);
    vec3& operator+=(const vec3 & other);
    vec3& operator*=(double t);
    vec3& operator/=(double t);
    double length() const;
    double length_squared() const;


};

inline std::ostream &operator<<(std::ostream &out, const vec3 &v);
inline vec3 operator+(const vec3 &u, const vec3 &v);
inline vec3 operator-(const vec3 &u, const vec3 &v);
inline vec3 operator*(const vec3 &u, const vec3 &v);
inline vec3 operator*(double t, const vec3 &v);
inline vec3 operator*(const vec3 &v, double t);
inline vec3 operator/(const vec3 &v, double t);
inline double dot(const vec3 &u, const vec3 &v);
inline vec3 cross(const vec3 &u, const vec3 &v);
inline vec3 unit_vector(const vec3 &v);

#endif