Thrust.h

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#ifndef CandUtils_Thrust_h
#define CandUtils_Thrust_h

#include "DataFormats/Math/interface/Vector3D.h"
#include "DataFormats/Candidate/interface/Candidate.h"
#include <vector>

class Thrust {
public:
  typedef math::XYZVector Vector;
  template <typename const_iterator>
  Thrust(const_iterator begin, const_iterator end) : thrust_(0), axis_(0, 0, 0), pSum_(0), n_(end - begin), p_(n_) {
    if (n_ == 0)
      return;
    std::vector<const reco::Candidate *> cands;
    for (const_iterator i = begin; i != end; ++i) {
      cands.push_back(&*i);
    }
    init(cands);
  }
  double thrust() const { return thrust_; }
  const Vector &axis() const { return axis_; }

private:
  double thrust_;
  Vector axis_;
  double pSum_;
  const unsigned int n_;
  std::vector<Vector> p_;

  struct ThetaPhi {
    ThetaPhi(double t, double p) : theta(t), phi(p) {}
    double theta, phi;
  };
  double thrust(const Vector &theAxis) const;
  ThetaPhi initialAxis() const;
  ThetaPhi finalAxis(ThetaPhi) const;
  Vector axis(double theta, double phi) const;
  Vector axis(const ThetaPhi &tp) const { return axis(tp.theta, tp.phi); }
  void parabola(double &a, double &b, double &c, const Vector &, const Vector &, const Vector &) const;
  void init(const std::vector<const reco::Candidate *> &);
};

#endif