AbsTrackRep Class Reference

Abstract base class for a track representation. More...

#include <AbsTrackRep.h>

Inheritance diagram for AbsTrackRep:

Collaboration diagram for AbsTrackRep:

Public Member Functions
	AbsTrackRep (int pdgCode, char propDir=0)
virtual AbsTrackRep *	clone () const =0
	Clone the trackRep.
virtual double	extrapolateToPlane (StateOnPlane &state, const genfit::SharedPlanePtr &plane, bool stopAtBoundary=false, bool calcJacobianNoise=false) const =0
	Extrapolates the state to plane, and returns the extrapolation length and, via reference, the extrapolated state. More...
virtual double	extrapolateToLine (StateOnPlane &state, const TVector3 &linePoint, const TVector3 &lineDirection, bool stopAtBoundary=false, bool calcJacobianNoise=false) const =0
	Extrapolates the state to the POCA to a line, and returns the extrapolation length and, via reference, the extrapolated state. More...
virtual double	extrapolateToLine (StateOnPlane &state, const TVector3 &point1, const TVector3 &point2, TVector3 &poca, TVector3 &dirInPoca, TVector3 &poca_onwire, bool stopAtBoundary=false, bool calcJacobianNoise=false) const
	Resembles the interface of GFAbsTrackRep in old versions of genfit. More...
virtual double	extrapolateToPoint (StateOnPlane &state, const TVector3 &point, bool stopAtBoundary=false, bool calcJacobianNoise=false) const =0
	Extrapolates the state to the POCA to a point, and returns the extrapolation length and, via reference, the extrapolated state. More...
virtual double	extrapolateToPoint (StateOnPlane &state, const TVector3 &point, const TMatrixDSym &G, bool stopAtBoundary=false, bool calcJacobianNoise=false) const =0
	Extrapolates the state to the POCA to a point in the metric of G, and returns the extrapolation length and, via reference, the extrapolated state. More...
virtual double	extrapolateToCylinder (StateOnPlane &state, double radius, const TVector3 &linePoint=TVector3(0., 0., 0.), const TVector3 &lineDirection=TVector3(0., 0., 1.), bool stopAtBoundary=false, bool calcJacobianNoise=false) const =0
	Extrapolates the state to the cylinder surface, and returns the extrapolation length and, via reference, the extrapolated state. More...
virtual double	extrapolateToCone (StateOnPlane &state, double radius, const TVector3 &linePoint=TVector3(0., 0., 0.), const TVector3 &lineDirection=TVector3(0., 0., 1.), bool stopAtBoundary=false, bool calcJacobianNoise=false) const =0
	Extrapolates the state to the cone surface, and returns the extrapolation length and, via reference, the extrapolated state. More...
virtual double	extrapolateToSphere (StateOnPlane &state, double radius, const TVector3 &point=TVector3(0., 0., 0.), bool stopAtBoundary=false, bool calcJacobianNoise=false) const =0
	Extrapolates the state to the sphere surface, and returns the extrapolation length and, via reference, the extrapolated state. More...
virtual double	extrapolateBy (StateOnPlane &state, double step, bool stopAtBoundary=false, bool calcJacobianNoise=false) const =0
	Extrapolates the state by step (cm) and returns the extrapolation length and, via reference, the extrapolated state. More...
double	extrapolateToMeasurement (StateOnPlane &state, const AbsMeasurement *measurement, bool stopAtBoundary=false, bool calcJacobianNoise=false) const
	extrapolate to an AbsMeasurement
virtual unsigned int	getDim () const =0
	Get the dimension of the state vector used by the track representation.
virtual TVector3	getPos (const StateOnPlane &state) const =0
	Get the cartesian position of a state.
virtual TVector3	getMom (const StateOnPlane &state) const =0
	Get the cartesian momentum vector of a state.
TVector3	getDir (const StateOnPlane &state) const
	Get the direction vector of a state.
virtual void	getPosMom (const StateOnPlane &state, TVector3 &pos, TVector3 &mom) const =0
	Get cartesian position and momentum vector of a state.
void	getPosDir (const StateOnPlane &state, TVector3 &pos, TVector3 &dir) const
	Get cartesian position and direction vector of a state.
virtual TVectorD	get6DState (const StateOnPlane &state) const
	Get the 6D state vector (x, y, z, p_x, p_y, p_z).
virtual TMatrixDSym	get6DCov (const MeasuredStateOnPlane &state) const =0
	Get the 6D covariance.
virtual void	getPosMomCov (const MeasuredStateOnPlane &state, TVector3 &pos, TVector3 &mom, TMatrixDSym &cov) const =0
	Translates MeasuredStateOnPlane into 3D position, momentum and 6x6 covariance.
virtual void	get6DStateCov (const MeasuredStateOnPlane &state, TVectorD &stateVec, TMatrixDSym &cov) const
	Translates MeasuredStateOnPlane into 6D state vector (x, y, z, p_x, p_y, p_z) and 6x6 covariance.
virtual double	getMomMag (const StateOnPlane &state) const =0
	get the magnitude of the momentum in GeV.
virtual double	getMomVar (const MeasuredStateOnPlane &state) const =0
	get the variance of the absolute value of the momentum .
int	getPDG () const
	Get the pdg code.
double	getPDGCharge () const
	Get the charge of the particle of the pdg code.
virtual double	getCharge (const StateOnPlane &state) const =0
	Get the (fitted) charge of a state. More...
virtual double	getQop (const StateOnPlane &state) const =0
	Get charge over momentum.
double	getMass (const StateOnPlane &state) const
	Get tha particle mass in GeV/c^2.
char	getPropDir () const
	Get propagation direction. (-1, 0, 1) -> (backward, auto, forward).
virtual void	getForwardJacobianAndNoise (TMatrixD &jacobian, TMatrixDSym &noise, TVectorD &deltaState) const =0
	Get the jacobian and noise matrix of the last extrapolation.
virtual void	getBackwardJacobianAndNoise (TMatrixD &jacobian, TMatrixDSym &noise, TVectorD &deltaState) const =0
	Get the jacobian and noise matrix of the last extrapolation if it would have been done in opposite direction.
virtual std::vector< genfit::MatStep >	getSteps () const =0
	Get stepsizes and material properties of crossed materials of the last extrapolation.
virtual double	getRadiationLenght () const =0
	Get the accumulated X/X0 (path / radiation length) of the material crossed in the last extrapolation.
virtual double	getTime (const StateOnPlane &) const =0
	Get the time corresponding to the StateOnPlane. Extrapolation.
void	calcJacobianNumerically (const genfit::StateOnPlane &origState, const genfit::SharedPlanePtr destPlane, TMatrixD &jacobian) const
	Calculate Jacobian of transportation numerically. More...
bool	switchPDGSign ()
	try to multiply pdg code with -1. (Switch from particle to anti-particle and vice versa).
virtual void	setPosMom (StateOnPlane &state, const TVector3 &pos, const TVector3 &mom) const =0
	Set position and momentum of state.
virtual void	setPosMom (StateOnPlane &state, const TVectorD &state6) const =0
	Set position and momentum of state.
virtual void	setPosMomErr (MeasuredStateOnPlane &state, const TVector3 &pos, const TVector3 &mom, const TVector3 &posErr, const TVector3 &momErr) const =0
	Set position and momentum and error of state.
virtual void	setPosMomCov (MeasuredStateOnPlane &state, const TVector3 &pos, const TVector3 &mom, const TMatrixDSym &cov6x6) const =0
	Set position, momentum and covariance of state.
virtual void	setPosMomCov (MeasuredStateOnPlane &state, const TVectorD &state6, const TMatrixDSym &cov6x6) const =0
	Set position, momentum and covariance of state.
virtual void	setChargeSign (StateOnPlane &state, double charge) const =0
	Set the sign of the charge according to charge.
virtual void	setQop (StateOnPlane &state, double qop) const =0
	Set charge/momentum.
virtual void	setTime (StateOnPlane &state, double time) const =0
	Set time at which the state was defined.
void	setPropDir (int dir)
	Set propagation direction. (-1, 0, 1) -> (backward, auto, forward).
void	switchPropDir ()
	Switch propagation direction. Has no effect if propDir_ is set to 0.
virtual bool	isSameType (const AbsTrackRep *other)=0
	check if other is of same type (e.g. RKTrackRep).
virtual bool	isSame (const AbsTrackRep *other)=0
	check if other is of same type (e.g. RKTrackRep) and has same pdg code.
virtual void	setDebugLvl (unsigned int lvl=1)
virtual void	Print (const Option_t *="") const

Protected Member Functions
	AbsTrackRep (const AbsTrackRep &)
	protect from calling copy c'tor from outside the class. Use clone() if you want a copy!
AbsTrackRep &	operator= (const AbsTrackRep &)
	protect from calling assignment operator from outside the class. Use clone() instead!

Protected Attributes
int	pdgCode_
	Particle code.
char	propDir_
	propagation direction (-1, 0, 1) -> (backward, auto, forward)
unsigned int	debugLvl_

Detailed Description

Abstract base class for a track representation.

Provides functionality to extrapolate a StateOnPlane to another DetPlane, to the POCA to a line or a point, or a cylinder or sphere. Defines a set of parameters describing the track. StateOnPlane objects are always defined with a track parameterization of a specific AbsTrackRep. The AbsTrackRep provides functionality to translate from the internal representation of a state into cartesian position and momentum (and covariance) and vice versa.

Definition at line 66 of file AbsTrackRep.h.

Member Function Documentation

calcJacobianNumerically()

void calcJacobianNumerically	(	const genfit::StateOnPlane &	origState,
		const genfit::SharedPlanePtr	destPlane,
		TMatrixD &	jacobian
	)		const

Calculate Jacobian of transportation numerically.

Slow but accurate. Can be used to validate (semi)analytic calculations.

Definition at line 105 of file AbsTrackRep.cc.

                                                                         {
 
  // Find the transport matrix for track propagation from origState to destPlane
  // I.e. this finds
  //            d stateDestPlane / d origState |_origState
 
  jacobian.ResizeTo(getDim(), getDim());
 
  // no science behind these values, I verified that forward and
  // backward propagation yield inverse matrices to good
  // approximation.  In order to avoid bad roundoff errors, the actual
  // step taken is determined below, separately for each direction.
  const double defaultStepX = 1.E-5;
  double stepX;
 
  // Calculate derivative for all three dimensions successively.
  // The algorithm follows the one in TF1::Derivative() :
  //   df(x) = (4 D(h/2) - D(h)) / 3
  // with D(h) = (f(x + h) - f(x - h)) / (2 h).
  //
  // Could perhaps do better by also using f(x) which would be stB.
  TVectorD rightShort(getDim()), rightFull(getDim());
  TVectorD leftShort(getDim()), leftFull(getDim());
  for (size_t i = 0; i < getDim(); ++i) {
    {
      genfit::StateOnPlane stateCopy(origState);
      double temp = stateCopy.getState()(i) + defaultStepX / 2;
      // Find the actual size of the step, which will differ from
      // defaultStepX due to roundoff.  This is the step-size we will
      // use for this direction.  Idea taken from Numerical Recipes,
      // 3rd ed., section 5.7.
      //
      // Note that if a number is exactly representable, it's double
      // will also be exact.  Outside denormals, this also holds for
      // halving.  Unless the exponent changes (which it only will in
      // the vicinity of zero) adding or subtracing doesn't make a
      // difference.
      //
      // We determine the roundoff error for the half-step.  If this
      // is exactly representable, the full step will also be.
      stepX = 2 * (temp - stateCopy.getState()(i));
      (stateCopy.getState())(i) = temp;
      extrapolateToPlane(stateCopy, destPlane);
      rightShort = stateCopy.getState();
    }
    {
      genfit::StateOnPlane stateCopy(origState);
      (stateCopy.getState())(i) -= stepX / 2;
      extrapolateToPlane(stateCopy, destPlane);
      leftShort = stateCopy.getState();
    }
    {
      genfit::StateOnPlane stateCopy(origState);
      (stateCopy.getState())(i) += stepX;
      extrapolateToPlane(stateCopy, destPlane);
      rightFull = stateCopy.getState();
    }
    {
      genfit::StateOnPlane stateCopy(origState);
      (stateCopy.getState())(i) -= stepX;
      extrapolateToPlane(stateCopy, destPlane);
      leftFull = stateCopy.getState();
    }
 
    // Calculate the derivatives for the individual components of
    // the track parameters.
    for (size_t j = 0; j < getDim(); ++j) {
      double derivFull = (rightFull(j) - leftFull(j)) / 2 / stepX;
      double derivShort = (rightShort(j) - leftShort(j)) / stepX;
 
      jacobian(j, i) = 1./3.*(4*derivShort - derivFull);
    }
  }
}

extrapolateBy()

virtual double extrapolateBy ( StateOnPlane &  state, double  step, bool  stopAtBoundary = false, bool  calcJacobianNoise = false  ) const

pure virtual

Extrapolates the state by step (cm) and returns the extrapolation length and, via reference, the extrapolated state.

If stopAtBoundary is true, the extrapolation stops as soon as a material boundary is encountered.

If state has a covariance, jacobian and noise matrices will be calculated and the covariance will be propagated. If state has no covariance, jacobian and noise will only be calculated if calcJacobianNoise == true.

Implemented in RKTrackRep.

extrapolateToCone()

virtual double extrapolateToCone ( StateOnPlane &  state, double  radius, const TVector3 &  linePoint = TVector3(0., 0., 0.), const TVector3 &  lineDirection = TVector3(0., 0., 1.), bool  stopAtBoundary = false, bool  calcJacobianNoise = false  ) const

pure virtual

Extrapolates the state to the cone surface, and returns the extrapolation length and, via reference, the extrapolated state.

If stopAtBoundary is true, the extrapolation stops as soon as a material boundary is encountered.

If state has a covariance, jacobian and noise matrices will be calculated and the covariance will be propagated. If state has no covariance, jacobian and noise will only be calculated if calcJacobianNoise == true.

Implemented in RKTrackRep.

extrapolateToCylinder()

virtual double extrapolateToCylinder ( StateOnPlane &  state, double  radius, const TVector3 &  linePoint = TVector3(0., 0., 0.), const TVector3 &  lineDirection = TVector3(0., 0., 1.), bool  stopAtBoundary = false, bool  calcJacobianNoise = false  ) const

pure virtual

Extrapolates the state to the cylinder surface, and returns the extrapolation length and, via reference, the extrapolated state.

If stopAtBoundary is true, the extrapolation stops as soon as a material boundary is encountered.

If state has a covariance, jacobian and noise matrices will be calculated and the covariance will be propagated. If state has no covariance, jacobian and noise will only be calculated if calcJacobianNoise == true.

Implemented in RKTrackRep.

extrapolateToLine() [1/2]

virtual double extrapolateToLine ( StateOnPlane &  state, const TVector3 &  linePoint, const TVector3 &  lineDirection, bool  stopAtBoundary = false, bool  calcJacobianNoise = false  ) const

pure virtual

Extrapolates the state to the POCA to a line, and returns the extrapolation length and, via reference, the extrapolated state.

If stopAtBoundary is true, the extrapolation stops as soon as a material boundary is encountered.

If state has a covariance, jacobian and noise matrices will be calculated and the covariance will be propagated. If state has no covariance, jacobian and noise will only be calculated if calcJacobianNoise == true.

Implemented in RKTrackRep.

extrapolateToLine() [2/2]

virtual double extrapolateToLine ( StateOnPlane &  state, const TVector3 &  point1, const TVector3 &  point2, TVector3 &  poca, TVector3 &  dirInPoca, TVector3 &  poca_onwire, bool  stopAtBoundary = false, bool  calcJacobianNoise = false  ) const

inlinevirtual

Resembles the interface of GFAbsTrackRep in old versions of genfit.

This interface to extrapolateToLine is intended to resemble the interface of GFAbsTrackRep in old versions of genfit and is implemented by default via the preceding function.

If stopAtBoundary is true, the extrapolation stops as soon as a material boundary is encountered.

If state has a covariance, jacobian and noise matrices will be calculated and the covariance will be propagated. If state has no covariance, jacobian and noise will only be calculated if calcJacobianNoise == true.

Definition at line 120 of file AbsTrackRep.h.

                                            {
    TVector3 wireDir(point2 - point1);
    wireDir = wireDir.Unit();
    double retval = this->extrapolateToLine(state, point1, wireDir, stopAtBoundary, calcJacobianNoise);
    poca = this->getPos(state);
    dirInPoca = this->getMom(state);
    dirInPoca = dirInPoca.Unit();
 
    poca_onwire = point1 + wireDir*((poca - point1)*wireDir);
    
    return retval;
  }

extrapolateToPlane()

virtual double extrapolateToPlane ( StateOnPlane &  state, const genfit::SharedPlanePtr &  plane, bool  stopAtBoundary = false, bool  calcJacobianNoise = false  ) const

pure virtual

Extrapolates the state to plane, and returns the extrapolation length and, via reference, the extrapolated state.

If stopAtBoundary is true, the extrapolation stops as soon as a material boundary is encountered.

If state has a covariance, jacobian and noise matrices will be calculated and the covariance will be propagated. If state has no covariance, jacobian and noise will only be calculated if calcJacobianNoise == true.

Implemented in RKTrackRep.

extrapolateToPoint() [1/2]

virtual double extrapolateToPoint ( StateOnPlane &  state, const TVector3 &  point, bool  stopAtBoundary = false, bool  calcJacobianNoise = false  ) const

pure virtual

Extrapolates the state to the POCA to a point, and returns the extrapolation length and, via reference, the extrapolated state.

If stopAtBoundary is true, the extrapolation stops as soon as a material boundary is encountered.

If state has a covariance, jacobian and noise matrices will be calculated and the covariance will be propagated. If state has no covariance, jacobian and noise will only be calculated if calcJacobianNoise == true.

Implemented in RKTrackRep.

extrapolateToPoint() [2/2]

virtual double extrapolateToPoint ( StateOnPlane &  state, const TVector3 &  point, const TMatrixDSym &  G, bool  stopAtBoundary = false, bool  calcJacobianNoise = false  ) const

pure virtual

Extrapolates the state to the POCA to a point in the metric of G, and returns the extrapolation length and, via reference, the extrapolated state.

If stopAtBoundary is true, the extrapolation stops as soon as a material boundary is encountered.

If state has a covariance, jacobian and noise matrices will be calculated and the covariance will be propagated. If state has no covariance, jacobian and noise will only be calculated if calcJacobianNoise == true.

Implemented in RKTrackRep.

extrapolateToSphere()

virtual double extrapolateToSphere ( StateOnPlane &  state, double  radius, const TVector3 &  point = TVector3(0., 0., 0.), bool  stopAtBoundary = false, bool  calcJacobianNoise = false  ) const

pure virtual

Extrapolates the state to the sphere surface, and returns the extrapolation length and, via reference, the extrapolated state.

If stopAtBoundary is true, the extrapolation stops as soon as a material boundary is encountered.

If state has a covariance, jacobian and noise matrices will be calculated and the covariance will be propagated. If state has no covariance, jacobian and noise will only be calculated if calcJacobianNoise == true.

Implemented in RKTrackRep.

getCharge()

virtual double getCharge ( const StateOnPlane &  state ) const

pure virtual

Get the (fitted) charge of a state.

This is not always equal the pdg charge (e.g. if the charge sign was flipped during the fit).

Implemented in RKTrackRep, and MplTrackRep.

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The documentation for this class was generated from the following files:

• genfit2/code2/core/include/AbsTrackRep.h
• genfit2/code2/core/src/AbsTrackRep.cc