SphericityEigenvalues.h

/**************************************************************************
 * BASF2 (Belle Analysis Framework 2)                                     *
 * Copyright(C) 2018 - Belle II Collaboration                             *
 *                                                                        *
 * Author: The Belle II Collaboration                                     *
 * Contributors:  Umberto Tamponi (tamponi@to.infn.it)                    *
 *                                                                        *
 * This software is provided "as is" without any warranty.                *
 **************************************************************************/
#pragma once
 
#include <TVector3.h>
 
namespace Belle2 {
  class SphericityEigenvalues {
  public:
 
    explicit SphericityEigenvalues(const std::vector<TVector3>& momenta)
    {
      m_momenta.clear();
      m_momenta = momenta;
    }
 
    ~SphericityEigenvalues() {};
 
 
    void setMomenta(const std::vector<TVector3>& momenta)
    {
      m_momenta.clear();
      m_momenta = momenta;
      return;
    }
 
 
    void calculateEigenvalues();
 
 
    double getEigenvalue(short i) const
    {
      return (i < 0 || i > 3) ? 0. : m_lambda[i];
    }
 
    TVector3 getEigenvector(short i) const
    {
      TVector3 nullVector(0., 0., 0.);
      return (i < 0 || i > 3) ? nullVector : m_eVector[i];
    }
 
  private:
 
    double m_lambda[3] = {0.}; 
    TVector3 m_eVector[3]; 
    std::vector<TVector3> m_momenta; 
  };
 
} // Belle2 namespace