SphericityEigenvalues.h

/**************************************************************************
 * basf2 (Belle II Analysis Software Framework)                           *
 * Author: The Belle II Collaboration                                     *
 *                                                                        *
 * See git log for contributors and copyright holders.                    *
 * This file is licensed under LGPL-3.0, see LICENSE.md.                  *
 **************************************************************************/
#pragma once
 
#include <Math/Vector3D.h>
#include <Math/Vector4D.h>
#include <vector>
 
namespace Belle2 {
 
  class SphericityEigenvalues {
  public:

    explicit SphericityEigenvalues(const std::vector<ROOT::Math::PxPyPzEVector>& momenta)
    {
      m_momenta.clear();
      m_momenta = momenta;
    }

    ~SphericityEigenvalues() {};
 

    void setMomenta(const std::vector<ROOT::Math::PxPyPzEVector>& momenta)
    {
      m_momenta.clear();
      m_momenta = momenta;
    }
 

    void calculateEigenvalues();
 

    double getEigenvalue(short i) const
    {
      return (i < 0 || i > 3) ? 0. : m_lambda[i];
    }

    ROOT::Math::XYZVector getEigenvector(short i) const
    {
      ROOT::Math::XYZVector nullVector(0., 0., 0.);
      return (i < 0 || i > 3) ? nullVector : m_eVector[i];
    }
 
  private:
 
    double m_lambda[3] = {0.}; 
    ROOT::Math::XYZVector m_eVector[3]; 
    std::vector<ROOT::Math::PxPyPzEVector> m_momenta; 
  };

} // Belle2 namespace