TrackConstraint Class Reference

Abstract base class for constraints of kinematic fits. More...

#include <TrackConstraint.h>

Inheritance diagram for TrackConstraint:

[legend]Collaboration diagram for TrackConstraint:

[legend]List of all members.

Public Member Functions
	TrackConstraint ()
	Creates an empty TrackConstraint object.
virtual	~TrackConstraint ()
	Virtual destructor.
virtual void	setFOList (std::vector< TrackFitObject * > *fitobjects_)
	Adds several TrackFitObject objects to the list.
virtual void	addToFOList (TrackFitObject &fitobject, int flag=1)
	Adds one TrackFitObject objects to the list.
virtual double	getValue () const=0
	Returns the value of the constraint.
virtual void	getDerivatives (int idim, double der[]) const=0
virtual void	add1stDerivativesToMatrix (int idim, double *M) const
	Adds first order derivatives to global covariance matrix M.
virtual void	add2ndDerivativesToMatrix (int idim, double *M, double lambda) const
	Adds second order derivatives to global covariance matrix M.
virtual int	getGlobalNum () const
	Accesses position of constraint in global constraint list.
virtual void	setGlobalNum (int iglobal)
	Sets position of constraint in global constraint list.
virtual void	invalidateCache () const
	Invalidates any cached values for the next event.
Protected Types
typedef std::vector< TrackFitObject * >	FitObjectContainer
	Vector of pointers to TrackFitObjects.
typedef FitObjectContainer::iterator	FitObjectIterator
	Iterator through vector of pointers to TrackFitObjects.
typedef FitObjectContainer::const_iterator	ConstFitObjectIterator
	Constant iterator through vector of pointers to TrackFitObjects.
Protected Attributes
FitObjectContainer	fitobjects
	The FitObjectContainer.
std::vector< double >	derivatives
	The derivatives.
std::vector< int >	flags
std::vector< double >	sign
int	globalNum
	Position of constraint in global constraint list.

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Detailed Description

Abstract base class for constraints of kinematic fits.

This class defines the minimal functionality any constraint class must provide. First of all a constraint should know on with particles (or FitObject) it is applied. Where as for example a constraint on the total transvese momentum takes into account all particles in the event, an invariant mass constraint usually applies only to a subset of particles.

The particle list is implemented as a vector containing pointers to objects derived from TrackFitObject and can be either set a whole (setFOList) or enlarged by adding a single TrackFitObject (addToFOList).

From the four--momenta of all concerned fit objects the constraint has to be able to calculate its current value (getValue). Constraints should be formulated such that a value of zero corresponds to a perfectly fulfilled constraint.

In order to find a solution to the constrained minimisation problem, fit algorithms usually need the first order derivatives of the constraint with respect to the fit parameters. Since many constraints can be most easily expressed in terms of E, px, py, pz, the constraints supply their derivatives w.r.t. these parameters. If a FitObject uses a different parametrisation, it is its own task to provide the additional derivatives of E, px, py, pz w.r.t. the parameters of the FitObject. Thus it is easily possible to use FitObjects with different kinds of parametrisations under the same constraint. Some fit algorithms also need the second derivatives of the constraint, i.e. the NewtonFitter.

First and second order derivatives of each constraint can be added directly to the global covariance matrix containing the derivatives of all constraints w.r.t. to all parameters (add1stDerivativesToMatrix, add2ndDerivativesToMatrix). This requires the constraint to know its position in the overall list of constraints (globalNum).

Author: Benno List, Jenny List

Date

2005/01/12 10:11:46

Author

blist

Definition at line 57 of file TrackConstraint.h.

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Member Typedef Documentation

typedef FitObjectContainer::const_iterator TrackConstraint::ConstFitObjectIterator [protected]

Constant iterator through vector of pointers to TrackFitObjects. Definition at line 105 of file TrackConstraint.h. Referenced by TrackMomentumConstraint::add1stDerivativesToMatrix().

typedef std::vector<TrackFitObject *> TrackConstraint::FitObjectContainer [protected]

Vector of pointers to TrackFitObjects. Definition at line 101 of file TrackConstraint.h.

typedef FitObjectContainer::iterator TrackConstraint::FitObjectIterator [protected]

Iterator through vector of pointers to TrackFitObjects. Definition at line 103 of file TrackConstraint.h.

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Constructor & Destructor Documentation

TrackConstraint::TrackConstraint (   )  [inline]

Creates an empty TrackConstraint object. Definition at line 120 of file TrackConstraint.h. References invalidateCache().

virtual TrackConstraint::~TrackConstraint (   )  [inline, virtual]

Virtual destructor. Definition at line 62 of file TrackConstraint.h.

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Member Function Documentation

virtual void TrackConstraint::add1stDerivativesToMatrix (  int  idim, double *  M )  const [inline, virtual]

Adds first order derivatives to global covariance matrix M. Implements BaseConstraint. Reimplemented in TrackMomentumConstraint. Definition at line 87 of file TrackConstraint.h.

virtual void TrackConstraint::add2ndDerivativesToMatrix (  int  idim, double *  M, double  lambda )  const [inline, virtual]

Adds second order derivatives to global covariance matrix M. Implements BaseConstraint. Reimplemented in TrackMomentumConstraint. Definition at line 89 of file TrackConstraint.h.

virtual void TrackConstraint::addToFOList (  TrackFitObject &  fitobject, int  flag = 1 )  [inline, virtual]

Adds one TrackFitObject objects to the list. Definition at line 74 of file TrackConstraint.h. References fitobjects, flags, and sign. Referenced by VertexFitObject::addMomentumConstraint().

virtual void TrackConstraint::getDerivatives (  int  idim, double  der[] )  const [pure virtual]

Get first order derivatives. Call this with a predefined array "der" with the necessary number of entries! Implements BaseConstraint. Implemented in TrackMomentumConstraint.

virtual int TrackConstraint::getGlobalNum (   )  const [inline, virtual]

Accesses position of constraint in global constraint list. Implements BaseConstraint. Definition at line 92 of file TrackConstraint.h. References globalNum. Referenced by TrackMomentumConstraint::add1stDerivativesToMatrix().

virtual double TrackConstraint::getValue (   )  const [pure virtual]

Returns the value of the constraint. Implements BaseConstraint. Implemented in TrackMomentumConstraint.

virtual void TrackConstraint::invalidateCache (   )  const [inline, virtual]

Invalidates any cached values for the next event. Reimplemented in TrackMomentumConstraint. Definition at line 97 of file TrackConstraint.h. Referenced by TrackConstraint().

virtual void TrackConstraint::setFOList (  std::vector< TrackFitObject * > *  fitobjects_  )  [inline, virtual]

Adds several TrackFitObject objects to the list. Parameters: fitobjects_  A list of BaseFitObject objects Definition at line 65 of file TrackConstraint.h. References fitobjects, flags, and sign.

virtual void TrackConstraint::setGlobalNum (  int  iglobal  )  [inline, virtual]

Sets position of constraint in global constraint list. Implements BaseConstraint. Definition at line 94 of file TrackConstraint.h. References globalNum.

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Member Data Documentation

std::vector<double> TrackConstraint::derivatives [protected]

The derivatives. Definition at line 109 of file TrackConstraint.h.

FitObjectContainer TrackConstraint::fitobjects [protected]

The FitObjectContainer. Definition at line 107 of file TrackConstraint.h. Referenced by TrackMomentumConstraint::add1stDerivativesToMatrix(), addToFOList(), TrackMomentumConstraint::getDerivatives(), TrackMomentumConstraint::getValue(), setFOList(), and TrackMomentumConstraint::updateCache().

std::vector<int> TrackConstraint::flags [protected]

The flags can be used to divide the FitObjectContainer into several subsets used for example to implement an equal mass constraint (see MassConstraint). Definition at line 112 of file TrackConstraint.h. Referenced by addToFOList(), TrackMomentumConstraint::getDerivatives(), TrackMomentumConstraint::getValue(), and setFOList().

int TrackConstraint::globalNum [protected]

Position of constraint in global constraint list. Definition at line 116 of file TrackConstraint.h. Referenced by getGlobalNum(), and setGlobalNum().

std::vector<double> TrackConstraint::sign [protected]

Definition at line 113 of file TrackConstraint.h. Referenced by addToFOList(), TrackMomentumConstraint::getDerivatives(), TrackMomentumConstraint::getValue(), and setFOList().

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

• TrackConstraint.h

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