MarlinKinfit  0.4.0
Public Member Functions | Protected Types | Protected Attributes | List of all members
TrackConstraint Class Referenceabstract

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

#include <TrackConstraint.h>

Inheritance diagram for TrackConstraint:
BaseConstraint

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. More...
 
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
 Get first order derivatives. More...
 
virtual void add1stDerivativesToMatrix (double *M, int idim) const
 Adds first order derivatives to global covariance matrix M. More...
 
virtual void add2ndDerivativesToMatrix (double *M, int idim, double lambda) const
 Adds second order derivatives to global covariance matrix M. More...
 
virtual void addToGlobalChi2DerVector (double *y, int idim, double lambda) const
 Add lambda times derivatives of chi squared to global derivative matrix. More...
 
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.
 
- Public Member Functions inherited from BaseConstraint
 BaseConstraint ()
 Creates an empty BaseConstraint object.
 
 BaseConstraint (const BaseConstraint &rhs)
 Copy constructor. More...
 
BaseConstraintoperator= (const BaseConstraint &rhs)
 Assignment. More...
 
virtual ~BaseConstraint ()
 Virtual destructor.
 
virtual double getError () const
 Returns the error on the value of the constraint.
 
virtual const char * getName () const
 Returns the name of the constraint.
 
virtual void setName (const char *name_)
 Set object's name.
 
virtual std::ostream & print (std::ostream &os) const
 print object to ostream More...
 

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
 The flags can be used to divide the FitObjectContainer into several subsets used for example to implement an equal mass constraint (see MassConstraint). More...
 
std::vector< double > sign
 
int globalNum
 Position of constraint in global constraint list.
 
- Protected Attributes inherited from BaseConstraint
char * name
 

Additional Inherited Members

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:
2008/01/30 09:14:54
Author:
blist

Member Function Documentation

virtual void TrackConstraint::add1stDerivativesToMatrix ( double *  M,
int  idim 
) const
inlinevirtual

Adds first order derivatives to global covariance matrix M.

Parameters
MCovariance matrix, at least idim x idim
idimFirst dimension of the array
virtual void TrackConstraint::add2ndDerivativesToMatrix ( double *  M,
int  idim,
double  lambda 
) const
inlinevirtual

Adds second order derivatives to global covariance matrix M.

Parameters
MGlobal covariance matrix, dimension at least idim x idim
idimFirst dimension of array der
lambdaLagrange multiplier for this constraint
virtual void TrackConstraint::addToGlobalChi2DerVector ( double *  y,
int  idim,
double  lambda 
) const
inlinevirtual

Add lambda times derivatives of chi squared to global derivative matrix.

Parameters
yVector of chi2 derivatives
idimVector size
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.

virtual void TrackConstraint::setFOList ( std::vector< TrackFitObject * > *  fitobjects_)
inlinevirtual

Adds several TrackFitObject objects to the list.

Parameters
fitobjects_A list of BaseFitObject objects

References fitobjects, and flags.

Member Data Documentation

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).

Referenced by addToFOList(), and setFOList().


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