DTRecSegment2D Class Reference

#include <DTRecSegment2D.h>

Inheritance diagram for DTRecSegment2D:

Public Member Functions
double	chi2 () const override
	the chi2 of the fit More...
DTRecSegment2D *	clone () const override
AlgebraicSymMatrix	covMatrix () const
	the Covariance Matrix More...
int	degreesOfFreedom () const override
	return the DOF of the segment More...
int	dimension () const override
	return 2. The dimension of the matrix More...
	DTRecSegment2D ()
	DTRecSegment2D (DetId id, const std::vector< DTRecHit1D > &hits)
	c'tor from hits More...
	DTRecSegment2D (DetId id, LocalPoint &position, LocalVector &direction, AlgebraicSymMatrix &covMatrix, double chi2, std::vector< DTRecHit1D > &hits1D)
	complete constructor More...
bool	ist0Valid () const
LocalVector	localDirection () const override
	the local direction in SL frame More...
LocalError	localDirectionError () const override
	the local direction error (xx,xy,yy) in SL frame: only xx is not 0. More...
LocalPoint	localPosition () const override
	local position in SL frame More...
LocalError	localPositionError () const override
	local position error in SL frame More...
AlgebraicVector	parameters () const override
	the vector of parameters (dx/dz,x) More...
AlgebraicSymMatrix	parametersError () const override
AlgebraicMatrix	projectionMatrix () const override
std::vector< const TrackingRecHit * >	recHits () const override
	Access to component RecHits (if any) More...
std::vector< TrackingRecHit * >	recHits () override
	Non-const access to component RecHits (if any) More...
std::vector< DTRecHit1D >	specificRecHits () const
	Access to specific components. More...
double	t0 () const
	Get the segment t0 (if recomputed, 0 is returned otherwise) More...
double	vDrift () const
	~DTRecSegment2D () override
	Destructor. More...
Public Member Functions inherited from RecSegment
	RecSegment (DetId id)
	RecSegment (TrackingRecHit::id_type id=0)
	~RecSegment () override
	Destructor. More...
Public Member Functions inherited from TrackingRecHit
virtual bool	canImproveWithTrack () const
RecHitPointer	cloneForFit (const GeomDet &idet) const
virtual TrackingRecHit *	cloneHit () const
virtual RecHitPointer	cloneSH () const
const GeomDet *	det () const
virtual const GeomDetUnit *	detUnit () const
virtual float	errorGlobalR () const
virtual float	errorGlobalRPhi () const
virtual float	errorGlobalZ () const
DetId	geographicalId () const
virtual void	getKfComponents (KfComponentsHolder &holder) const
unsigned int	getRTTI () const
Type	getType () const
virtual GlobalPoint	globalPosition () const
virtual GlobalError	globalPositionError () const
virtual bool	hasPositionAndError () const
	to be redefined by daughter class More...
virtual TrackingRecHit const *	hit () const
bool	isValid () const
id_type	rawId () const
virtual void	recHitsV (std::vector< const TrackingRecHit * > &) const
virtual void	recHitsV (std::vector< TrackingRecHit * > &)
virtual void	setDet (const GeomDet &idet)
virtual bool	sharesInput (const TrackingRecHit *other, SharedInputType what) const
virtual const Surface *	surface () const
	TrackingRecHit (DetId id, Type type=valid)
	TrackingRecHit (id_type id=0, Type type=valid)
	TrackingRecHit (DetId id, unsigned int rt, Type type=valid)
	TrackingRecHit (const GeomDet &idet, Type type=valid)
	TrackingRecHit (const GeomDet &idet, unsigned int rt, Type type=valid)
	TrackingRecHit (const GeomDet &idet, TrackingRecHit const &rh)
virtual ConstRecHitContainer	transientHits () const
Type	type () const
virtual float	weight () const
virtual	~TrackingRecHit ()

Protected Member Functions
void	setChi2 (const double &chi2)
void	setCovMatrix (const AlgebraicSymMatrix &cov)
void	setDirection (const LocalVector &dir)
void	setPosition (const LocalPoint &pos)
void	setT0 (const double &t0)
void	setVdrift (const double &vdrift)
void	update (std::vector< DTRecHit1D > &updatedRecHits)
Protected Member Functions inherited from TrackingRecHit
void	setId (id_type iid)
void	setRTTI (unsigned int rt)
void	setType (Type ttype)

Protected Attributes
double	theChi2
AlgebraicSymMatrix	theCovMatrix
LocalVector	theDirection
std::vector< DTRecHit1D >	theHits
LocalPoint	thePosition
double	theT0
double	theVdrift

Private Member Functions
AlgebraicVector	param (const LocalPoint &lp, const LocalVector &lv) const

Static Private Attributes
static const AlgebraicMatrix	theProjectionMatrix {initTheProjectionMatrix()}

Friends
class	DTSegmentUpdator

Additional Inherited Members
Public Types inherited from TrackingRecHit
typedef std::vector< ConstRecHitPointer >	ConstRecHitContainer
using	ConstRecHitPointer = std::shared_ptr< TrackingRecHit const >
typedef unsigned int	id_type
typedef std::vector< ConstRecHitPointer >	RecHitContainer
using	RecHitPointer = std::shared_ptr< TrackingRecHit const >
enum	SharedInputType { all, some }
	definition of equality via shared input More...
enum	Type {   valid = 0, missing = 1, inactive = 2, bad = 3,   missing_inner = 4, missing_outer = 5, inactive_inner = 6, inactive_outer = 7 }
Static Public Attributes inherited from TrackingRecHit
static const int	rttiShift = 24
static const int	typeMask = 0xf

Detailed Description

Base class for 2-parameters segments measuring position and direction in X projection.

Implements the AbstractDetMeasurement part of the interface for 2D RecHits in terms of localPosition() and localPositionError() and Direction. This segment is measuring the position and the direction in just one projection, the "X". Typical use case is a segment reconstructed only in X projection. To be used as base class for all 2D positional-directional segments. The coordinate measured is assumend to be the local "x" and "dx/dz"

2D Segments for the muon barrel system. 2D means that this segment has information about position and direction in one projection (r-phi or r-theta/zeta).

Author

Stefano Lacaprara - INFN Legnaro stefa.nosp@m.no.l.nosp@m.acapr.nosp@m.ara@.nosp@m.pd.in.nosp@m.fn.i.nosp@m.t

Riccardo Bellan - INFN TO ricca.nosp@m.rdo..nosp@m.bella.nosp@m.n@ce.nosp@m.rn.ch

Definition at line 45 of file DTRecSegment2D.h.

Constructor & Destructor Documentation

DTRecSegment2D::DTRecSegment2D ( )

inline

Constructor empty c'tor needed by POOL (I guess)

Definition at line 51 of file DTRecSegment2D.h.

References chi2(), covMatrix(), hfClusterShapes_cfi::hits, position, and ~DTRecSegment2D().

Referenced by clone().

: theChi2(0.0), theT0(0.), theVdrift(0.) {}

DTRecSegment2D::DTRecSegment2D	(	DetId	id,
		const std::vector< DTRecHit1D > &	hits
	)

c'tor from hits

Definition at line 57 of file DTRecSegment2D.cc.

                                                                       :
  RecSegment(id), theChi2(0.0), theT0(0.), theVdrift(0.), theHits(hits){
}

DTRecSegment2D::DTRecSegment2D	(	DetId	id,
		LocalPoint &	position,
		LocalVector &	direction,
		AlgebraicSymMatrix &	covMatrix,
		double	chi2,
		std::vector< DTRecHit1D > &	hits1D
	)

complete constructor

Definition at line 61 of file DTRecSegment2D.cc.

                                         :
 RecSegment(id), thePosition(position),theDirection(direction),
  theCovMatrix(covMatrix),theChi2(chi2),theT0(0.),theVdrift(0.),theHits(hits1D){}

DTRecSegment2D::~DTRecSegment2D ( )

override

Destructor.

Definition at line 55 of file DTRecSegment2D.cc.

Referenced by DTRecSegment2D().

{}

Member Function Documentation

double DTRecSegment2D::chi2 ( void  ) const

inlineoverridevirtual

the chi2 of the fit

Implements RecSegment.

Definition at line 101 of file DTRecSegment2D.h.

References degreesOfFreedom(), recHits(), specificRecHits(), and theChi2.

Referenced by DTRecSegment4D::chi2(), DTChamberRecSegment2D::DTChamberRecSegment2D(), DTRecSegment2D(), DTSLRecSegment2D::DTSLRecSegment2D(), DTSegmentUpdator::fit(), operator<<(), DTRefitAndCombineReco4D::refitSuperSegments(), DTCombinatorialPatternReco4D::segmentSpecialZed(), and setChi2().

{ return theChi2; }

DTRecSegment2D* DTRecSegment2D::clone ( void  ) const

inlineoverridevirtual

Implements TrackingRecHit.

Reimplemented in DTSLRecSegment2D.

Definition at line 67 of file DTRecSegment2D.h.

References DTRecSegment2D().

{ return new DTRecSegment2D(*this);}

AlgebraicSymMatrix DTRecSegment2D::covMatrix ( ) const

inline

the Covariance Matrix

Definition at line 116 of file DTRecSegment2D.h.

References theCovMatrix.

Referenced by DTChamberRecSegment2D::DTChamberRecSegment2D(), DTRecSegment2D(), DTRecSegment4D::DTRecSegment4D(), DTSLRecSegment2D::DTSLRecSegment2D(), and DTCombinatorialPatternReco4D::segmentSpecialZed().

{return theCovMatrix;}

int DTRecSegment2D::degreesOfFreedom ( ) const

overridevirtual

return the DOF of the segment

Implements RecSegment.

Definition at line 77 of file DTRecSegment2D.cc.

References dimension(), and theHits.

Referenced by DTLocalTriggerSynchTask::analyze(), chi2(), DTRecSegment4D::degreesOfFreedom(), and operator<<().

                                           {
  return theHits.size()-dimension();
}

int DTRecSegment2D::dimension ( ) const

inlineoverridevirtual

return 2. The dimension of the matrix

Implements RecSegment.

Definition at line 86 of file DTRecSegment2D.h.

Referenced by degreesOfFreedom().

{ return 2;}

bool DTRecSegment2D::ist0Valid ( ) const

inline

Definition at line 120 of file DTRecSegment2D.h.

References theT0.

Referenced by TrackDetectorAssociator::addTAMuonSegmentMatch(), DTLocalTriggerSynchTask::analyze(), DTTimingExtractor::fillTiming(), CosmicMuonTrajectoryBuilder::t0(), and DTSegmentUpdator::updateHits().

{return (theT0 > -998.) ? true : false;}

LocalVector DTRecSegment2D::localDirection ( ) const

inlineoverridevirtual

the local direction in SL frame

Implements RecSegment.

Definition at line 95 of file DTRecSegment2D.h.

References localDirectionError(), and theDirection.

Referenced by DTVDriftCalibration::analyze(), DTSegment2DQuality::dqmAnalyze(), DTSegment2DSLPhiQuality::dqmAnalyze(), DTSegment4DQuality::dqmAnalyze(), DTRecSegment4D::DTRecSegment4D(), DTSegmentUpdator::fit(), operator<<(), parameters(), DTCombinatorialPatternReco4D::segmentSpecialZed(), and DTSegmentUpdator::update().

{ return theDirection; }

LocalError DTRecSegment2D::localDirectionError ( ) const

overridevirtual

the local direction error (xx,xy,yy) in SL frame: only xx is not 0.

Implements RecSegment.

Definition at line 73 of file DTRecSegment2D.cc.

References theCovMatrix.

Referenced by DTSegment2DQuality::dqmAnalyze(), DTSegment2DSLPhiQuality::dqmAnalyze(), DTSegment4DQuality::dqmAnalyze(), and localDirection().

                                                    {
  return LocalError(theCovMatrix[0][0],0.,0.);
}

LocalPoint DTRecSegment2D::localPosition ( ) const

inlineoverridevirtual

local position in SL frame

Implements TrackingRecHit.

Definition at line 89 of file DTRecSegment2D.h.

References localPositionError(), and thePosition.

Referenced by DTVDriftCalibration::analyze(), DTSegment2DQuality::dqmAnalyze(), DTSegment2DSLPhiQuality::dqmAnalyze(), DTSegment4DQuality::dqmAnalyze(), DTRecSegment4D::DTRecSegment4D(), DTSegmentUpdator::fit(), operator<<(), parameters(), DTCombinatorialPatternReco4D::segmentSpecialZed(), and DTSegmentUpdator::update().

{return thePosition; }

LocalError DTRecSegment2D::localPositionError ( ) const

overridevirtual

local position error in SL frame

Implements TrackingRecHit.

Definition at line 69 of file DTRecSegment2D.cc.

References theCovMatrix.

Referenced by DTSegment2DQuality::dqmAnalyze(), DTSegment2DSLPhiQuality::dqmAnalyze(), DTSegment4DQuality::dqmAnalyze(), localPosition(), and DTCombinatorialPatternReco4D::segmentSpecialZed().

                                                    {
  return LocalError(theCovMatrix[1][1],0.,0.);
}

AlgebraicVector DTRecSegment2D::param ( const LocalPoint &  lp, const LocalVector &  lv  ) const

inlineprivate

Definition at line 155 of file DTRecSegment2D.h.

References operator<<(), mps_fire::result, PV3DBase< T, PVType, FrameType >::x(), and PV3DBase< T, PVType, FrameType >::z().

Referenced by parameters().

                                                                            {
    AlgebraicVector result(2);
    result[1]=lp.x();
    result[0]=lv.x()/lv.z();
    return result;
  }

AlgebraicVector DTRecSegment2D::parameters ( void  ) const

inlineoverridevirtual

the vector of parameters (dx/dz,x)

Implements TrackingRecHit.

Definition at line 71 of file DTRecSegment2D.h.

References localDirection(), localPosition(), param(), and parametersError().

Referenced by Vispa.Plugins.ConfigEditor.ConfigDataAccessor.ConfigDataAccessor::inputTags(), Vispa.Plugins.ConfigEditor.ConfigDataAccessor.ConfigDataAccessor::properties(), and Vispa.Plugins.ConfigEditor.ConfigDataAccessor.ConfigDataAccessor::recursePSetProperties().

                                              {
    return param( localPosition(), localDirection());
  }

AlgebraicSymMatrix DTRecSegment2D::parametersError ( ) const

overridevirtual

mat[0][0]=sigma (dx/dz) mat[1][1]=sigma (x) mat[0][1]=cov(dx/dz,x)

Implements TrackingRecHit.

Definition at line 30 of file DTRecSegment2D.cc.

References funct::m.

Referenced by DTSegmentUpdator::fit(), parameters(), and DTRecSegment4D::setCovMatrixForZed().

                                                         {
  AlgebraicSymMatrix m(2);
  // if ( det().alignmentPositionError()) {
  //   LocalError lape = 
  //     ErrorFrameTransformer().transform( det().alignmentPositionError()->globalError(), 
  //                                        det().surface());
  //   m[0][0] = lv.xx();
  //   m[0][1] = 0.;
  //   m[1][1] = lp.xx()+lape.xx();
  // } else {
    m[0][0] = theCovMatrix[0][0];
    m[0][1] = theCovMatrix[0][1];
    m[1][1] = theCovMatrix[1][1];
  //};

    //cout << "theCovMatrix elements " << theCovMatrix[0][0] << " , " << theCovMatrix[0][1] <<
    //        " , " << theCovMatrix[1][0] << " , " << theCovMatrix[1][1] << endl;

  return m;

}

AlgebraicMatrix DTRecSegment2D::projectionMatrix ( ) const

inlineoverridevirtual

return the projection matrix, which must project a parameter vector, whose components are (q/p, dx/dz, dy/dz, x, y), into the vector returned by parameters()

Implements TrackingRecHit.

Definition at line 81 of file DTRecSegment2D.h.

References theProjectionMatrix.

                                                    {
    return theProjectionMatrix;
  }

std::vector< const TrackingRecHit * > DTRecSegment2D::recHits ( ) const

overridevirtual

Access to component RecHits (if any)

Implements TrackingRecHit.

Definition at line 88 of file DTRecSegment2D.cc.

References theHits.

Referenced by chi2(), DTSegment4DQuality::dqmAnalyze(), DTChamberEfficiencyTask::getBestSegment(), MuonAssociatorByHitsHelper::getMatchedIds(), TrackerMuonHitExtractor::getMuonHits(), DTChamberEfficiencyTask::isGoodSegment(), MuonSegmentMatcher::matchDT(), operator<<(), and MuonTrackProducer::produce().

                                                               {

  std::vector<const TrackingRecHit*> pointersOfRecHits; 
  
  for(std::vector<DTRecHit1D>::const_iterator rechit = theHits.begin();
      rechit != theHits.end(); rechit++)
    pointersOfRecHits.push_back( &(*rechit) );
  
  return pointersOfRecHits;
}

std::vector< TrackingRecHit * > DTRecSegment2D::recHits ( )

overridevirtual

Non-const access to component RecHits (if any)

Implements TrackingRecHit.

Definition at line 99 of file DTRecSegment2D.cc.

References theHits.

                                                   {

  std::vector<TrackingRecHit*> pointersOfRecHits; 
    
  for(std::vector<DTRecHit1D>::iterator rechit = theHits.begin();
      rechit != theHits.end(); rechit++)
    pointersOfRecHits.push_back( &(*rechit) );
  
  return pointersOfRecHits;
}

void DTRecSegment2D::setChi2 ( const double &  chi2 )

protected

Definition at line 130 of file DTRecSegment2D.cc.

References chi2(), and theChi2.

Referenced by DTSegmentUpdator::fit().

                                               {
  theChi2=chi2;
}

void DTRecSegment2D::setCovMatrix ( const AlgebraicSymMatrix &  cov )

protected

Definition at line 126 of file DTRecSegment2D.cc.

References theCovMatrix.

Referenced by DTSegmentUpdator::fit().

                                                              { 
  theCovMatrix = cov;
}

void DTRecSegment2D::setDirection ( const LocalVector &  dir )

protected

Definition at line 122 of file DTRecSegment2D.cc.

References dir, and theDirection.

Referenced by DTSegmentUpdator::fit().

                                                       {
  theDirection=dir;
}

void DTRecSegment2D::setPosition ( const LocalPoint &  pos )

protected

Definition at line 118 of file DTRecSegment2D.cc.

References thePosition.

Referenced by DTSegmentUpdator::fit().

                                                     {
  thePosition= pos;
}

void DTRecSegment2D::setT0 ( const double &  t0 )

protected

Definition at line 134 of file DTRecSegment2D.cc.

References t0(), and theT0.

Referenced by DTSegmentUpdator::calculateT0corr(), and DTSegmentUpdator::fit().

                                          {
  theT0=t0;
}

void DTRecSegment2D::setVdrift ( const double &  vdrift )

protected

Definition at line 138 of file DTRecSegment2D.cc.

References theVdrift.

Referenced by DTSegmentUpdator::calculateT0corr().

                                                  {
  theVdrift=vdrift;
}

std::vector< DTRecHit1D > DTRecSegment2D::specificRecHits

(

)

const

Access to specific components.

Definition at line 110 of file DTRecSegment2D.cc.

References theHits.

Referenced by TrackDetectorAssociator::addTAMuonSegmentMatch(), DTSegmentsTask::analyze(), DTResidualCalibration::analyze(), DTVDriftCalibration::analyze(), SegmentTrackAnalyzer::analyze(), DTEfficiencyTask::analyze(), DTResolutionAnalysisTask::analyze(), DTSegmentAnalysisTask::analyze(), FWDTSegmentProxyBuilder::buildViewType(), DTSegmentUpdator::calculateT0corr(), chi2(), DTCalibValidationFromMuons::compute(), DTCalibValidation::compute(), DTTimingExtractor::fillTiming(), DTSegmentUpdator::fit(), MuonSegmentMatcher::matchDT(), DTSegmentSelector::operator()(), DTSegmentUpdator::rejectBadHits(), DTCombinatorialPatternReco4D::segmentSpecialZed(), CosmicMuonTrajectoryBuilder::t0(), and DTSegmentUpdator::updateHits().

                                                            {
  return theHits;
}

double DTRecSegment2D::t0 ( ) const

inline

Get the segment t0 (if recomputed, 0 is returned otherwise)

Definition at line 119 of file DTRecSegment2D.h.

References theT0.

Referenced by TrackDetectorAssociator::addTAMuonSegmentMatch(), DTSegment4DQuality::dqmAnalyze(), DTTimingExtractor::fillTiming(), DTSegmentUpdator::fit(), setT0(), CosmicMuonTrajectoryBuilder::t0(), and DTSegmentUpdator::updateHits().

{return theT0;}

void DTRecSegment2D::update ( std::vector< DTRecHit1D > &  updatedRecHits )

protected

Definition at line 114 of file DTRecSegment2D.cc.

References theHits.

Referenced by progressbar.ProgressBar::__next__(), MatrixUtil.Matrix::__setitem__(), MatrixUtil.Steps::__setitem__(), Vispa.Gui.VispaWidget.VispaWidget::autosize(), Vispa.Views.LineDecayView.LineDecayContainer::createObject(), Vispa.Views.LineDecayView.LineDecayContainer::deselectAllObjects(), Vispa.Gui.VispaWidgetOwner.VispaWidgetOwner::deselectAllWidgets(), Vispa.Gui.VispaWidget.VispaWidget::enableAutosizing(), dqm-mbProfile.Profile::finish(), progressbar.ProgressBar::finish(), Vispa.Gui.MenuWidget.MenuWidget::leaveEvent(), Vispa.Gui.VispaWidgetOwner.VispaWidgetOwner::mouseMoveEvent(), Vispa.Gui.MenuWidget.MenuWidget::mouseMoveEvent(), Vispa.Views.LineDecayView.LineDecayContainer::mouseMoveEvent(), Vispa.Gui.VispaWidgetOwner.VispaWidgetOwner::mouseReleaseEvent(), Vispa.Views.LineDecayView.LineDecayContainer::objectMoved(), MatrixUtil.Steps::overwrite(), DTSegmentUpdator::rejectBadHits(), Vispa.Views.LineDecayView.LineDecayContainer::removeObject(), Vispa.Gui.ConnectableWidget.ConnectableWidget::removePorts(), Vispa.Gui.FindDialog.FindDialog::reset(), Vispa.Gui.PortConnection.PointToPointConnection::select(), Vispa.Gui.VispaWidget.VispaWidget::select(), Vispa.Views.LineDecayView.LineDecayContainer::select(), Vispa.Gui.VispaWidget.VispaWidget::setText(), Vispa.Gui.VispaWidget.VispaWidget::setTitle(), Vispa.Gui.ZoomableWidget.ZoomableWidget::setZoom(), Vispa.Views.LineDecayView.LineDecayContainer::setZoom(), Vispa.Gui.PortConnection.PointToPointConnection::updateConnection(), and DTSegmentUpdator::updateHits().

                                                                 {
  theHits = updatedRecHits;
}

double DTRecSegment2D::vDrift ( ) const

inline

Get the vDirft as computed by the algo for the computation of the segment t0 (if recomputed, 0 is returned otherwise)

Definition at line 124 of file DTRecSegment2D.h.

References theVdrift.

Referenced by DTSegmentUpdator::updateHits().

{return theVdrift;}

Friends And Related Function Documentation

friend class DTSegmentUpdator

friend

Definition at line 127 of file DTRecSegment2D.h.

Member Data Documentation

double DTRecSegment2D::theChi2

protected

Definition at line 144 of file DTRecSegment2D.h.

Referenced by chi2(), and setChi2().

AlgebraicSymMatrix DTRecSegment2D::theCovMatrix

protected

mat[0][0]=sigma (dx/dz) mat[1][1]=sigma (x) mat[0][1]=cov(dx/dz,x)

Definition at line 142 of file DTRecSegment2D.h.

Referenced by covMatrix(), localDirectionError(), localPositionError(), and setCovMatrix().

LocalVector DTRecSegment2D::theDirection

protected

Definition at line 137 of file DTRecSegment2D.h.

Referenced by localDirection(), and setDirection().

std::vector<DTRecHit1D> DTRecSegment2D::theHits

protected

Definition at line 148 of file DTRecSegment2D.h.

Referenced by degreesOfFreedom(), recHits(), specificRecHits(), and update().

LocalPoint DTRecSegment2D::thePosition

protected

Definition at line 136 of file DTRecSegment2D.h.

Referenced by localPosition(), and setPosition().

const AlgebraicMatrix DTRecSegment2D::theProjectionMatrix {initTheProjectionMatrix()}

staticprivate

Definition at line 153 of file DTRecSegment2D.h.

Referenced by initTheProjectionMatrix(), and projectionMatrix().

double DTRecSegment2D::theT0

protected

Definition at line 145 of file DTRecSegment2D.h.

Referenced by ist0Valid(), setT0(), and t0().

double DTRecSegment2D::theVdrift

protected

Definition at line 146 of file DTRecSegment2D.h.

Referenced by setVdrift(), and vDrift().