TwoTrackMinimumDistanceLineLine Class Reference

#include <TwoTrackMinimumDistanceLineLine.h>

Public Member Functions
bool	calculate (const GlobalTrajectoryParameters &, const GlobalTrajectoryParameters &)
double	firstAngle () const
std::pair< double, double >	pathLength () const
std::pair< GlobalPoint, GlobalPoint >	points () const
double	secondAngle () const

Private Attributes
GlobalPoint	gPos
GlobalPoint	hPos
double	pathG
double	pathH
double	phiG
double	phiH

Detailed Description

This is a helper class for TwoTrackMinimumDistance. No user should need direct access to this class. Exact solution.

Definition at line 17 of file TwoTrackMinimumDistanceLineLine.h.

Member Function Documentation

bool TwoTrackMinimumDistanceLineLine::calculate	(	const GlobalTrajectoryParameters &	theG,
		const GlobalTrajectoryParameters &	theH
	)

Calculates the point of closest approach on the two tracks.

Returns

false in case of success
true in case of failure. Possible failures:

• Either of the Trajectories are charged
• Either of the Trajectories is of zero momentum
• Trajectories are parallel

Definition at line 7 of file TwoTrackMinimumDistanceLineLine.cc.

References GlobalTrajectoryParameters::charge(), Vector3DBase< T, FrameTag >::dot(), gPos, hPos, MagneticField::inTesla(), PV3DBase< T, PVType, FrameType >::mag(), GlobalTrajectoryParameters::magneticField(), GlobalTrajectoryParameters::momentum(), pathG, pathH, PV3DBase< T, PVType, FrameType >::phi(), phiG, phiH, GlobalTrajectoryParameters::position(), and PV3DBase< T, PVType, FrameType >::z().

                                                                                        {
  GlobalPoint gOrig = theG.position();
  GlobalPoint hOrig = theH.position();
  bool isLineG = theG.magneticField().inTesla(gOrig).z() == 0 || theG.charge() == 0;
  bool isLineH = theH.magneticField().inTesla(hOrig).z() == 0 || theH.charge() == 0;
  if (!(isLineG && isLineH)) {
    edm::LogWarning("TwoTrackMinimumDistanceLineLine")
        << "charge of input track is not zero or field non zero"
        << "\n positions: " << gOrig << " , " << hOrig << "\n Bz fields: " << theG.magneticField().inTesla(gOrig).z()
        << " , " << theH.magneticField().inTesla(hOrig).z() << "\n charges: " << theG.charge() << " , "
        << theH.charge();
    return true;
  };

  GlobalVector gVec = theG.momentum();
  const double gMag = theG.momentum().mag();
  double gMag2 = gMag * gMag;
  GlobalVector hVec = theH.momentum();
  const double hMag = theH.momentum().mag();
  double hMag2 = hMag * hMag;

  if (gMag == 0. || hMag == 0.) {
    edm::LogWarning("TwoTrackMinimumDistanceLineLine") << "momentum of input trajectory is zero.";
    return true;
  };

  phiG = theG.momentum().phi();
  phiH = theH.momentum().phi();

  double gVec_Dot_hVec = gVec.dot(hVec);
  double norm = gVec_Dot_hVec * gVec_Dot_hVec - gMag2 * hMag2;

  if (norm == 0) {
    edm::LogWarning("TwoTrackMinimumDistanceLineLine") << "Tracks are parallel.";
    return true;
  }

  GlobalVector posDiff = gOrig - hOrig;

  double tG = (posDiff.dot(gVec) * hMag2 - gVec_Dot_hVec * posDiff.dot(hVec)) / norm;
  double tH = (gVec_Dot_hVec * posDiff.dot(gVec) - posDiff.dot(hVec) * gMag2) / norm;

  gPos = GlobalPoint(gOrig + tG * gVec);
  hPos = GlobalPoint(hOrig + tH * hVec);
  //   cout << "TwoTrackMinimumDistanceLineLine "<<gPos<<hPos<<endl;

  pathG = tG * gMag;
  pathH = tH * hMag;
  return false;
}

double TwoTrackMinimumDistanceLineLine::firstAngle ( ) const

inline

Definition at line 34 of file TwoTrackMinimumDistanceLineLine.h.

References phiG.

{ return phiG; }

std::pair< double, double > TwoTrackMinimumDistanceLineLine::pathLength

(

)

const

Definition at line 63 of file TwoTrackMinimumDistanceLineLine.cc.

References pathG, and pathH.

                                                                          {
  return std::pair<double, double>(pathG, pathH);
}

std::pair< GlobalPoint, GlobalPoint > TwoTrackMinimumDistanceLineLine::points

(

)

const

Definition at line 59 of file TwoTrackMinimumDistanceLineLine.cc.

References gPos, and hPos.

                                                                                {
  return std::pair<GlobalPoint, GlobalPoint>(gPos, hPos);
}

double TwoTrackMinimumDistanceLineLine::secondAngle ( ) const

inline

Definition at line 35 of file TwoTrackMinimumDistanceLineLine.h.

References phiH.

{ return phiH; }

Member Data Documentation

GlobalPoint TwoTrackMinimumDistanceLineLine::gPos

private

Definition at line 40 of file TwoTrackMinimumDistanceLineLine.h.

Referenced by calculate(), and points().

GlobalPoint TwoTrackMinimumDistanceLineLine::hPos

private

Definition at line 40 of file TwoTrackMinimumDistanceLineLine.h.

Referenced by calculate(), and points().

double TwoTrackMinimumDistanceLineLine::pathG

private

Definition at line 39 of file TwoTrackMinimumDistanceLineLine.h.

Referenced by calculate(), and pathLength().

double TwoTrackMinimumDistanceLineLine::pathH

private

Definition at line 39 of file TwoTrackMinimumDistanceLineLine.h.

Referenced by calculate(), and pathLength().

double TwoTrackMinimumDistanceLineLine::phiG

private

Definition at line 38 of file TwoTrackMinimumDistanceLineLine.h.

Referenced by calculate(), and firstAngle().

double TwoTrackMinimumDistanceLineLine::phiH

private

Definition at line 38 of file TwoTrackMinimumDistanceLineLine.h.

Referenced by calculate(), and secondAngle().