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

#include <BaseHardConstraint.h>

Inheritance diagram for BaseHardConstraint:

Public Member Functions
virtual	~BaseHardConstraint ()
	Virtual destructor.

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 vector. More...

virtual double	dirDer (double p, double w, int idim, double mu=1)
	Calculate directional derivative. More...

virtual double	dirDerAbs (double p, double w, int idim, double mu=1)
	Calculate directional derivative for abs(c) More...

virtual bool	secondDerivatives (int i, int j, double *derivatives) const =0
	Second derivatives with respect to the meta-variables of Fit objects i and j; result false if all derivatives are zero. More...

virtual bool	firstDerivatives (int i, double *derivatives) const =0
	First derivatives with respect to the meta-variables of Fit objects i; result false if all derivatives are zero. More...

virtual int	getVarBasis () const =0

virtual double	getValue () const =0
	Returns the value of the constraint.

virtual double	getError () const
	Returns the error on the value of the constraint.

virtual void	getDerivatives (int idim, double der[]) const =0
	Get first order derivatives. 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. More...

virtual void	printFirstDerivatives () const

virtual void	printSecondDerivatives () const

virtual void	test1stDerivatives ()

virtual void	test2ndDerivatives ()

virtual double	num1stDerivative (int ifo, int ilocal, double eps)
	Evaluates numerically the 1st derivative w.r.t. a parameter. More...

virtual double	num2ndDerivative (int ifo1, int ilocal1, double eps1, int ifo2, int ilocal2, double eps2)
	Evaluates numerically the 2nd derivative w.r.t. 2 parameters. More...

Public Member Functions inherited from BaseConstraint
	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 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 < BaseFitObject * >	FitObjectContainer
	Vector of pointers to ParticleFitObjects.

typedef FitObjectContainer::iterator	FitObjectIterator
	Iterator through vector of pointers to ParticleFitObjects.

typedef FitObjectContainer::const_iterator	ConstFitObjectIterator
	Constant iterator through vector of pointers to ParticleFitObjects.

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...

int	globalNum
	Position of constraint in global constraint list.

Protected Attributes inherited from BaseConstraint
char *	name

Additional Inherited Members
Related Functions inherited from BaseConstraint
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

Member Function Documentation

void BaseHardConstraint::add1stDerivativesToMatrix	(	double *	M,
		int	idim
	)		const

virtual

Adds first order derivatives to global covariance matrix M.

Parameters

M	Global covariance matrix, dimension at least idim x idim
idim	First dimension of array der

References firstDerivatives(), fitobjects, and getGlobalNum().

void BaseHardConstraint::add2ndDerivativesToMatrix	(	double *	M,
		int	idim,
		double	lambda
	)		const

virtual

Adds second order derivatives to global covariance matrix M.

Calculates the second derivative of the constraint g w.r.t.

the various parameters, multiplies it by lambda and adds it to the global covariance matrix

in case of particlefitobject: We denote with P_i the 4-vector of the i-th ParticleFitObject, then $$ { ^2 g}{ a_k a_l} = { ^2 g}{ P_i P_j} { P_i}{ a_k} { P_j}{ a_l}

{ g}{ P_i} {^2 P_i}{ a_k a_l} $$ Here, ${ P_i}{ a_k}$ is a $4 n_i$ Matrix, where $n_i$ is the number of parameters of FitObject i; Correspondingly, ${^2 P_i}{ a_k a_l}$ is a $4 n_i n_i$ matrix. Also, ${ ^2 g}{ P_i P_j}$ is a $4 4$ matrix for a given i and j, and ${ g}{ P_i}$ is a 4-vector (though not a Lorentz-vector!).

but here it's been generalised

First, treat the part $$ { ^2 g}{ P_i P_j} { P_i}{ a_k} { P_j}{ a_l} $$

Second, treat the part $$ { g}{ P_i} {^2 P_i}{ a_k a_l} $$ Here, ${ g}{ P_i}$ is a 4-vector, which we pass on to the FitObject

Parameters

M	Global covariance matrix, dimension at least idim x idim
idim	First dimension of array der
lambda	Lagrange multiplier for this constraint

References firstDerivatives(), fitobjects, BaseFitObject::getGlobalParNum(), BaseFitObject::getNPar(), and secondDerivatives().

void BaseHardConstraint::addToGlobalChi2DerVector	(	double *	y,
		int	idim,
		double	lambda
	)		const

virtual

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

Parameters

y	Vector of chi2 derivatives
idim	Vector size

References BaseFitObject::addToGlobalChi2DerVector(), firstDerivatives(), and fitobjects.

Referenced by dirDer().

double BaseHardConstraint::dirDer	(	double *	p,
		double *	w,
		int	idim,
		double	mu = `1`
	)

virtual

Calculate directional derivative.

Parameters

p	Vector of direction
w	Work vector
idim	Vector size
mu	optional multiplier

References addToGlobalChi2DerVector().

Referenced by dirDerAbs().

double BaseHardConstraint::dirDerAbs	(	double *	p,
		double *	w,
		int	idim,
		double	mu = `1`
	)

virtual

Calculate directional derivative for abs(c)

Parameters

p	Vector of direction
w	Work vector
idim	Vector size
mu	optional multiplier

References dirDer(), and getValue().

virtual bool BaseHardConstraint::firstDerivatives	(	int	i,
		double *	derivatives
	)		const

pure virtual

First derivatives with respect to the meta-variables of Fit objects i; result false if all derivatives are zero.

Parameters

i	number of 1st FitObject
derivatives	The result 4-vector

Implemented in MomentumConstraint, MassConstraint, and VertexConstraint.

Referenced by add1stDerivativesToMatrix(), add2ndDerivativesToMatrix(), addToGlobalChi2DerVector(), and getError().

virtual void BaseHardConstraint::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!

Parameters

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

Implements BaseConstraint.

Implemented in MassConstraint, MomentumConstraint, and VertexConstraint.

double BaseHardConstraint::num1stDerivative	(	int	ifo,
		int	ilocal,
		double	eps
	)

virtual

Evaluates numerically the 1st derivative w.r.t. a parameter.

Parameters

ifo	Number of FitObject
ilocal	Local parameter number
eps	variation of local parameter

References fitobjects, BaseFitObject::getParam(), getValue(), and BaseFitObject::setParam().

double BaseHardConstraint::num2ndDerivative	(	int	ifo1,
		int	ilocal1,
		double	eps1,
		int	ifo2,
		int	ilocal2,
		double	eps2
	)

virtual

Evaluates numerically the 2nd derivative w.r.t. 2 parameters.

Parameters

ifo1	Number of 1st FitObject
ilocal1	1st local parameter number
eps1	variation of 1st local parameter
ifo2	Number of 1st FitObject
ilocal2	1st local parameter number
eps2	variation of 2nd local parameter

References fitobjects, BaseFitObject::getParam(), getValue(), and BaseFitObject::setParam().

virtual bool BaseHardConstraint::secondDerivatives	(	int	i,
		int	j,
		double *	derivatives
	)		const

pure virtual

Second derivatives with respect to the meta-variables of Fit objects i and j; result false if all derivatives are zero.

Parameters

i	number of 1st FitObject
j	number of 2nd FitObject
derivatives	The result 4x4 matrix

Implemented in MomentumConstraint, MassConstraint, and VertexConstraint.

Referenced by add2ndDerivativesToMatrix().

virtual void BaseHardConstraint::setGlobalNum ( int iglobal )

inlinevirtual

Sets position of constraint in global constraint list.

Parameters

iglobal Global constraint number

References globalNum.

Referenced by NewtonFitterGSL::initialize(), and NewFitterGSL::initialize().

Member Data Documentation

std::vector<int> BaseHardConstraint::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 ParticleConstraint::addToFOList(), MassConstraint::firstDerivatives(), MassConstraint::getDerivatives(), MassConstraint::getMass(), MassConstraint::getValue(), ParticleConstraint::resetFOList(), MassConstraint::secondDerivatives(), and ParticleConstraint::setFOList().

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

Public Member Functions

Protected Types

Protected Attributes

Additional Inherited Members

Detailed Description

Member Function Documentation

Member Data Documentation