// TwoVector class, polar coord. version
// Glen Cowan, RHUL Physics Dept., October 2004

#ifndef TWOVECTOR_H
#define TWOVECTOR_H

class TwoVector {
  public:
    TwoVector();
    TwoVector(double x, double y);
    double x() const;
    double y() const;
    double r() const;
    double cosTheta() const;
    double sinTheta() const;
    double theta() const;
    void set(double x, double y);
    void setX(double);
    void setY(double);
    void setR(double);            // keeps theta constant
    void setTheta(double);        // keeps r constant
    void rotate(double);          // also as non-member function (below)
    TwoVector operator+(const TwoVector&);
    TwoVector operator-(const TwoVector&);
    TwoVector& operator+=(const TwoVector&);
    TwoVector& operator-=(const TwoVector&);
  private:
    double m_r;
    double m_theta;
};

// non-member operators and functions

TwoVector operator*(const TwoVector&, double);    // mult. by constant
TwoVector operator*(double, const TwoVector&);    // allow either order

double    dot(const TwoVector&, const TwoVector&);
TwoVector rotate (const TwoVector&, double);

#endif