GlobalTrajectoryParameters.h

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#ifndef _TRACKER_GLOBALTRAJECTORYPARAMETERS_H_
#define _TRACKER_GLOBALTRAJECTORYPARAMETERS_H_

#include "DataFormats/GeometryVector/interface/GlobalPoint.h"
#include "DataFormats/GeometryVector/interface/GlobalVector.h"
#include "DataFormats/TrajectoryState/interface/TrackCharge.h"
#include "DataFormats/Math/interface/AlgebraicROOTObjects.h"

class MagneticField;
class GlobalTrajectoryParameters {
public:
// construct
  GlobalTrajectoryParameters() :
    theField(nullptr), 
    theX(), theP(), 
    theCharge(0)
  {}  // we must initialize cache to non-NAN to avoid FPE

  GlobalTrajectoryParameters(
                            const GlobalPoint& aX,
                            const GlobalVector& aP,
                            TrackCharge aCharge,
                            const MagneticField* fieldProvider) :
    theField(fieldProvider),
    theX(aX), theP(aP),
    theCharge(aCharge)
    {setCache();}

  GlobalTrajectoryParameters(const GlobalPoint& aX,
                             const GlobalVector& aP,
                             TrackCharge aCharge,
                             const MagneticField* fieldProvider,
                             GlobalVector fieldValue):
    theField(fieldProvider),
    theX(aX), theP(aP),
    cachedMagneticField(fieldValue),
    theCharge(aCharge)
    {}



  GlobalTrajectoryParameters(const GlobalPoint& aX,
                             const GlobalVector& direction,
                             float transverseCurvature, int, 
                 const MagneticField* fieldProvider);


  GlobalTrajectoryParameters(const GlobalPoint& aX,
                             const GlobalVector& direction,
                             float transverseCurvature, int,
                             const MagneticField* fieldProvider,  
                             GlobalVector fieldValue);


  GlobalPoint position() const {
    return theX;
  }

  GlobalVector momentum() const {
    return theP;
  }

  GlobalVector direction() const {
    return theP.unit();
  }

  TrackCharge charge() const {
    return theCharge;
  }

  float signedInverseMomentum() const {
    return theCharge/theP.mag();
  }

  float signedInverseTransverseMomentum() const {
    return theCharge/theP.perp();
  }

  float transverseCurvature() const {
    return -2.99792458e-3f * signedInverseTransverseMomentum() * cachedMagneticField.z();
  }

  AlgebraicVector6 vector() const {
    return AlgebraicVector6(theX.x(),theX.y(),theX.z(),theP.x(),theP.y(),theP.z());
  }

 
  GlobalVector magneticFieldInInverseGeV( const GlobalPoint& x) const; 
  GlobalVector magneticFieldInInverseGeV() const {
    return 2.99792458e-3f * cachedMagneticField;
  }

  GlobalVector magneticFieldInTesla() const {
    return cachedMagneticField;
  }

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

private:
  void setCache();

private:
  const MagneticField* theField;
  GlobalPoint theX;
  GlobalVector theP;
  GlobalVector cachedMagneticField;
  signed char  theCharge;

};

#endif