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

#include <SoftGaussParticleConstraint.h>

Inheritance diagram for SoftGaussParticleConstraint:

Public Member Functions
	SoftGaussParticleConstraint (double sigma_)
	Creates an empty SoftGaussParticleConstraint object. More...

virtual	~SoftGaussParticleConstraint ()
	Virtual destructor.

virtual void	setFOList (std::vector< ParticleFitObject * > *fitobjects_)
	Adds several ParticleFitObject objects to the list. More...

virtual void	addToFOList (ParticleFitObject &fitobject, int flag=1)
	Adds one ParticleFitObject objects to the list.

virtual void	resetFOList ()
	Resests ParticleFitObject list.

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

virtual double	getChi2 () const
	Returns the chi2.

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

virtual double	getSigma () const
	Returns the sigma.

virtual double	setSigma (double sigma_)
	Sets the sigma. More...

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

virtual void	add2ndDerivativesToMatrix (double *M, int idim) const
	Adds second order derivatives to global covariance matrix M. More...

virtual void	addToGlobalChi2DerVector (double *y, int idim) const
	Add derivatives of chi squared to global derivative matrix. More...

virtual void	invalidateCache () const
	Invalidates any cached values for the next event.

void	test1stDerivatives ()

void	test2ndDerivatives ()

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

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...

int	getVarBasis () const

Public Member Functions inherited from BaseSoftConstraint
virtual	~BaseSoftConstraint ()
	Virtual destructor.

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
enum	{ VAR_BASIS =BaseDefs::VARBASIS_EPXYZ }

typedef std::vector < ParticleFitObject * >	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 Member Functions
virtual bool	secondDerivatives (int i, int j, double *derivatives) const =0
	Second derivatives with respect to the 4-vectors 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 4-vector of Fit objects i; result false if all derivatives are zero. More...

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...

double	sigma
	The sigma of the Gaussian.

Protected Attributes inherited from BaseSoftConstraint
char *	name

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 ParticleFitObject and can be either set a whole (setFOList) or enlarged by adding a single ParticleFitObject (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

Date:: 2008/02/13 12:37:38

Author:: blist

Constructor & Destructor Documentation

SoftGaussParticleConstraint::SoftGaussParticleConstraint ( double sigma_ )

Creates an empty SoftGaussParticleConstraint object.

Parameters

sigma_ The sigma value

References invalidateCache().

Member Function Documentation

void SoftGaussParticleConstraint::add2ndDerivativesToMatrix	(	double *	M,
		int	idim
	)		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 and adds it to the global covariance matrix

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!).

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

Second, treat the parts $$ { g}{ P_i} {^2 P_i}{ a_k a_l} $$ and $$ {^2 h}{ g^2} { g}{ P_i} { P_i}{ a_k} { g}{ P_j} { P_j}{ a_l} $$

Here, ${ g}{ P_i}$ is a 4-vector, which we pass on to the FitObject

Parameters

M	Covariance matrix, at least idim x idim
idim	First dimension of the array

Implements BaseSoftConstraint.

References BaseFitObject::addToGlobalChi2DerVector(), firstDerivatives(), fitobjects, BaseFitObject::getGlobalParNum(), BaseFitObject::getNPar(), getSigma(), getValue(), and secondDerivatives().

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

virtual

Add derivatives of chi squared to global derivative matrix.

Parameters

y	Vector of chi2 derivatives
idim	Vector size

Implements BaseSoftConstraint.

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

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

protectedpure virtual

First derivatives with respect to the 4-vector of Fit objects i; result false if all derivatives are zero.

Parameters

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

Implemented in SoftGaussMassConstraint, and SoftGaussMomentumConstraint.

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

virtual void SoftGaussParticleConstraint::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 SoftGaussMassConstraint, and SoftGaussMomentumConstraint.

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

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, getChi2(), BaseFitObject::getParam(), and BaseFitObject::setParam().

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

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, getChi2(), BaseFitObject::getParam(), and BaseFitObject::setParam().

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

protectedpure virtual

Second derivatives with respect to the 4-vectors 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 SoftGaussMassConstraint, and SoftGaussMomentumConstraint.

Referenced by add2ndDerivativesToMatrix().

virtual void SoftGaussParticleConstraint::setFOList ( std::vector< ParticleFitObject * > * fitobjects_ )

inlinevirtual

Adds several ParticleFitObject objects to the list.

Parameters

fitobjects_ A list of BaseFitObject objects

References fitobjects, and flags.

double SoftGaussParticleConstraint::setSigma ( double sigma_ )

virtual

Sets the sigma.

Parameters

sigma_ The new sigma value

References sigma.

Member Data Documentation

std::vector<int> SoftGaussParticleConstraint::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(), SoftGaussMassConstraint::firstDerivatives(), SoftGaussMassConstraint::getDerivatives(), SoftGaussMassConstraint::getMass(), SoftGaussMassConstraint::getValue(), resetFOList(), SoftGaussMassConstraint::secondDerivatives(), and setFOList().

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

Public Member Functions

Protected Types

Protected Member Functions

Protected Attributes

Additional Inherited Members

Detailed Description

Constructor & Destructor Documentation

Member Function Documentation

Member Data Documentation