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