ThreeVector.h

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// Class ThreeVector
//
// Author: Benno List
// Last update: $Date: 2005/01/12 10:11:46 $
//          by: $Author: blist $
// 
// Description: class for three-vectors
//               

#ifndef __THREEVECTOR_H
#define __THREEVECTOR_H

#include <iostream>
#include <cmath>

class ThreeVector {
  public:
    inline ThreeVector();
    inline ThreeVector(double px_, double py_, double pz_);
    // automatically generated copy constructor and assignment is fine
    
    inline double getPx()    const;
    inline double getPy()    const;
    inline double getPz()    const;
    inline double getX()     const;
    inline double getY()     const;
    inline double getZ()     const;
    
    inline double getP2()    const;
    inline double getP()     const;
    inline double getMag()   const;
    inline double getPt2()   const;
    inline double getPt()    const;
    inline double getR()     const;
    
    inline double getPhi()   const;
    inline double getTheta() const;
    inline double getEta()   const;
    
    inline double getComponent (int i) const;
    
    inline ThreeVector& setValues(double px_, double py_, double pz_);

    inline ThreeVector& ThreeVector::operator+= (const ThreeVector& rhs);
    inline ThreeVector& ThreeVector::operator-= (const ThreeVector& rhs);
    inline ThreeVector& ThreeVector::operator*= (double rhs);
    
  private:
    double px, py, pz;
};

ThreeVector::ThreeVector()
: px(0), py(0), pz(0)
{}

ThreeVector::ThreeVector(double px_, double py_, double pz_)
: px(px_), py(py_), pz(pz_)
{}
    
double ThreeVector::getPx() const { return px; }
double ThreeVector::getPy() const { return py; }
double ThreeVector::getPz() const { return pz; }
double ThreeVector::getX()  const { return px; }
double ThreeVector::getY()  const { return py; }
double ThreeVector::getZ()  const { return pz; }

double ThreeVector::getPt2() const { return px*px + py*py; }
double ThreeVector::getPt()  const { return std::sqrt(getPt2()); }
double ThreeVector::getR()   const { return std::sqrt(getPt2()); }

double ThreeVector::getP2() const { return px*px + py*py + pz*pz; }
double ThreeVector::getP()  const { return std::sqrt(getP2()); }
double ThreeVector::getMag()const { return std::sqrt(getP2()); }

double ThreeVector::getPhi()   const { return std::atan2(py, px); }
double ThreeVector::getTheta() const { return std::atan2(getPt(), pz); }
double ThreeVector::getEta() const { return -std::log(std::tan(0.5*getTheta())); }

double ThreeVector::getComponent(int i) const { 
  switch (i) {
    case 0: return getPx();
    case 1: return getPy();
    case 2: return getPz();
  }
  return NAN; // not-a-number, defined in cmath
}

ThreeVector& ThreeVector::setValues(double px_, double py_, double pz_) {
  px = px_;
  py = py_;
  pz = pz_;
  return *this;
}


ThreeVector& ThreeVector::operator+= (const ThreeVector& rhs) {
  px += rhs.px;
  py += rhs.py;
  pz += rhs.pz;
  return *this;
}

ThreeVector& ThreeVector::operator-= (const ThreeVector& rhs) {
  px -= rhs.px;
  py -= rhs.py;
  pz -= rhs.pz;
  return *this;
}

ThreeVector& ThreeVector::operator*= (double rhs) {
  px *= rhs;
  py *= rhs;
  pz *= rhs;
  return *this;
}

inline ThreeVector operator+ (const ThreeVector& lhs, const ThreeVector& rhs) {
  return ThreeVector (lhs.getPx()+rhs.getPx(), lhs.getPy()+rhs.getPy(), lhs.getPz()+rhs.getPz());
}

inline ThreeVector operator- (const ThreeVector& lhs, const ThreeVector& rhs) {
  return ThreeVector (lhs.getPx()-rhs.getPx(), lhs.getPy()-rhs.getPy(), lhs.getPz()-rhs.getPz());
}

inline ThreeVector operator- (const ThreeVector& rhs) {
  return ThreeVector (-rhs.getPx(), -rhs.getPy(), -rhs.getPz());
}

inline double operator* (const ThreeVector& lhs, const ThreeVector& rhs) {
  return lhs.getPx()*rhs.getPx() + lhs.getPy()*rhs.getPy() + lhs.getPz()*rhs.getPz();
}

inline ThreeVector operator* (double lhs, const ThreeVector& rhs) {
  return ThreeVector (lhs*rhs.getPx(), lhs*rhs.getPy(), lhs*rhs.getPz());
}
    
inline std::ostream& operator<< (std::ostream& out, const ThreeVector& v) {
  out << "(" << v.getPx() << ", " << v.getPy() << ", " << v.getPz() << ")";
  return out;
}



#endif // __THREEVECTOR_H

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