/data/refman/pasoursint/CMSSW_4_1_8_patch9/src/TrackingTools/GeomPropagators/interface/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 <cmath>
#include <cfloat>

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


class AnalyticalPropagator : public Propagator {

public:

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

  ~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;

  TrajectoryStateOnSurface propagate(const FreeTrajectoryState& fts, 
                                     const Plane& plane) const {
    return propagateWithPath(fts,plane).first;
  }
  std::pair<TrajectoryStateOnSurface,double> 
  propagateWithPath(const FreeTrajectoryState& fts, 
                    const Plane& plane) const; 
  
  TrajectoryStateOnSurface propagate(const FreeTrajectoryState& fts, 
                                     const Cylinder& cylinder) const {
    return propagateWithPath(fts,cylinder).first;
  }
  std::pair<TrajectoryStateOnSurface,double> 
  propagateWithPath(const FreeTrajectoryState& fts, 
                    const Cylinder& cylinder) const;
  virtual bool setMaxDirectionChange( float phiMax) { 
    theMaxDPhi2 = phiMax*phiMax;
    return true;
  }
  
#ifndef CMS_NO_RELAXED_RETURN_TYPE
  virtual AnalyticalPropagator * clone() const 
#else
    virtual Propagator * clone() const
#endif
  {
    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;

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

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

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

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

#endif