CollinearityConstraint.h

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/*
  Copyright (C) 2002-2020 CERN for the benefit of the ATLAS collaboration
*/
 
#ifndef TrkVertexKinematicFitterUtils_CollinearityConstraint_h 
#define TrkVertexKinematicFitterUtils_CollinearityConstraint_h 
 
// This object defines a Collinearity constraint to be used with the constrained kinematic vertex fitter
// It minimizes the angles between the tracks (phi in the x-y plane and theta in the z-plane) using scalar products
 
#include "TrkVertexFitterInterfaces/IKinematicConstraint.h"
 
namespace Trk {
class CollinearityConstraint : public IKinematicConstraint
{
public:
 
 
  CollinearityConstraint() = default;
  virtual ~CollinearityConstraint() = default;
 
  virtual Amg::VectorX vectorOfValues(
    std::vector<Amg::VectorX>& cart_coordList,
    std::vector<int>& charges,
    Amg::Vector3D refPoint,
    double b_fieldTesla) const override final;
 
  virtual Amg::MatrixX matrixOfDerivatives(
    std::vector<Amg::VectorX>& cart_coordList,
    std::vector<int>& charges,
    Amg::Vector3D refPoint,
    double b_fieldTesla) const override final;
 
  virtual int numberOfEquations() const override final { return s_eqno; }
 
private:
  static constexpr int s_eqno = 2; // number of constraint-equations used
};
}
 
#endif //TrkVertexKinematicFitterUtils_CollinearityConstraint_h