AnalyticalPropagator.h

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#ifndef _COMMONRECO_ANALYTICALPROPAGATOR_H_
#define _COMMONRECO_ANALYTICALPROPAGATOR_H_

#include "TrackingTools/GeomPropagators/interface/Propagator.h"
#include "TrackingTools/TrajectoryState/interface/TrajectoryStateOnSurface.h"
#include "FWCore/Utilities/interface/Visibility.h"

#include <cmath>
#include <cfloat>

class Surface;
class Cylinder;
class Plane;
class HelixPlaneCrossing;
class MagneticField; 


class AnalyticalPropagator final : public Propagator {

public:
  
  AnalyticalPropagator( const MagneticField* field,
                PropagationDirection dir = alongMomentum,
            float maxDPhi = 1.6,bool isOld=true) :
    Propagator(dir),
    theMaxDPhi2(maxDPhi*maxDPhi),
    theMaxDBzRatio(0.5),
    theField(field),
    isOldPropagationType(isOld) {}

  ~AnalyticalPropagator() {}

  //
  // use base class methods where necessary:
  // - propagation from TrajectoryStateOnSurface 
  //     (will use propagation from FreeTrajectoryState)
  // - propagation to general Surface
  //     (will use specialised methods for planes or cylinders)
  //
  using Propagator::propagate;
  using Propagator::propagateWithPath;
  
 private:
  std::pair<TrajectoryStateOnSurface,double> 
    propagateWithPath(const FreeTrajectoryState& fts, 
            const Plane& plane) const override; 
  

  std::pair<TrajectoryStateOnSurface,double> 
  propagateWithPath(const FreeTrajectoryState& fts, 
            const Cylinder& cylinder) const override;


 public:
  virtual bool setMaxDirectionChange( float phiMax) override { 
    theMaxDPhi2 = phiMax*phiMax;
    return true;
  }
  
  virtual AnalyticalPropagator * clone() const override
  {
    return new AnalyticalPropagator(*this);
  }
  
  void setMaxRelativeChangeInBz (const float maxDBz) {
    theMaxDBzRatio = maxDBz;
  }


private:
  std::pair<TrajectoryStateOnSurface,double> 
  propagatedStateWithPath (const FreeTrajectoryState& fts, 
               const Surface& surface, 
               const GlobalTrajectoryParameters& gtp, 
               const double& s) const dso_internal;

  bool propagateParametersOnCylinder(const FreeTrajectoryState& fts, 
                     const Cylinder& cylinder, 
                     GlobalPoint& x, 
                     GlobalVector& p, 
                     double& s) const dso_internal;

  bool propagateParametersOnPlane(const FreeTrajectoryState& fts, 
                  const Plane& plane, 
                  GlobalPoint& x, 
                  GlobalVector& p, 
                  double& s) const dso_internal;
  
  bool propagateWithLineCrossing(const GlobalPoint&, const GlobalVector&, 
                 const Plane&, GlobalPoint&, double&) const dso_internal;
  bool propagateWithLineCrossing(const GlobalPoint&, const GlobalVector&, 
                 const Cylinder&, GlobalPoint&, double&) const dso_internal;
  bool propagateWithHelixCrossing(HelixPlaneCrossing&, const Plane&, const float,
                  GlobalPoint&, GlobalVector&, double& s) const dso_internal;

  virtual const MagneticField* magneticField() const override {return theField;}

private:
  typedef std::pair<TrajectoryStateOnSurface,double> TsosWP;
  float theMaxDPhi2;
  float theMaxDBzRatio;
  const MagneticField* theField;
  bool isOldPropagationType;
};

#endif