BaseConstraint Class Reference

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

#include <BaseConstraint.h>

Inheritance diagram for BaseConstraint:

Public Member Functions
	BaseConstraint ()
	Creates an empty BaseConstraint object.
	BaseConstraint (const BaseConstraint &rhs)
	Copy constructor. More...
BaseConstraint &	operator= (const BaseConstraint &rhs)
	Assignment. More...
virtual	~BaseConstraint ()
	Virtual destructor.
virtual double	getValue () const =0
	Returns the value of the constraint function.
virtual double	getError () const
	Returns the error on the value of the constraint.
virtual const char *	getName () const
	Returns the name of the constraint.
void	setName (const char *name_)
	Set object's name.
virtual void	getDerivatives (int idim, double der[]) const =0
	Get first order derivatives of the constraint function Call this with a predefined array "der" with the necessary number of entries! More...
virtual std::ostream &	print (std::ostream &os) const
	print object to ostream More...

Protected Attributes
char *	name

Related Functions
(Note that these are not member functions.)
std::ostream &	operator<< (std::ostream &os, const BaseConstraint &bc)
	Prints out a BaseConstraint, using its print method. More...

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 BaseFitObject and can be either set a whole (setFOList) or enlarged by adding a single BaseFitObject (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: Jenny List, Benno List Last update:

Date

2011/03/03 15:03:02

by:

Author

blist

Definition at line 71 of file BaseConstraint.h.

Constructor & Destructor Documentation

BaseConstraint()

BaseConstraint

(

const BaseConstraint &

rhs

)

Copy constructor.

Parameters

rhs	right hand side

Definition at line 36 of file BaseConstraint.cc.

      : name(nullptr)
    {
      if (rhs.name) setName(rhs.name);
      else setName("???");
    }

Member Function Documentation

getDerivatives()

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

pure virtual

Get first order derivatives of the constraint function Call this with a predefined array "der" with the necessary number of entries!

Parameters

idim	First dimension of array der
der	Array of derivatives, dimension at least idim x idim

Implemented in SoftGaussParticleConstraint, BaseHardConstraint, SoftGaussMomentumConstraint, SoftGaussMassConstraint, RecoilMassConstraint, MomentumConstraint, MassConstraint, and TrackConstraint.

operator=()

BaseConstraint & operator=

(

const BaseConstraint &

rhs

)

Assignment.

Parameters

rhs	right hand side

Definition at line 42 of file BaseConstraint.cc.

print()

std::ostream & print ( std::ostream &  os ) const

virtual

print object to ostream

Parameters

os	The output stream

Definition at line 76 of file BaseConstraint.cc.

Friends And Related Function Documentation

operator<<()

std::ostream & operator<< ( std::ostream &  os, const BaseConstraint &  bc  )

related

Prints out a BaseConstraint, using its print method.

Parameters

os	The output stream
bc	The object to print

Definition at line 114 of file BaseConstraint.h.

    {
      return bc.print(os);
    }

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

• analysis/OrcaKinFit/include/BaseConstraint.h
• analysis/OrcaKinFit/src/BaseConstraint.cc