Extension of the FCNBase for the Fumili method.

Fumili applies only to minimization problems used for fitting. The method is based on a linearization of the model function negleting second derivatives. User needs to provide the model function. The figure-of-merit describing the difference between the model function and the actual measurements in the case of chi-square is the sum of the squares of the figures-of-merit calculated for each measurement point, which is implemented by the operator() member function. The user still has to implement the calculation of the individual figures-of-merit (which in the majority of the cases will be the (measured Value - the Value predicted by the model)/standard deviation implemeted by the FumiliStandardChi2FCN; however this form can become more complicated (see for an example Numerical Recipes' section on "Straight-Line Data with Errors in Both Coordinates")).

Author: Andras Zsenei and Lorenzo Moneta, Creation date: 24 Aug 2004

See Also: MINUIT Tutorial on function minimization, section 5; FumiliStandardChi2FCN

Definition at line 52 of file FumiliChi2FCN.h.

Public Member Functions
	FumiliChi2FCN ()

virtual	~FumiliChi2FCN ()

void	SetModelFunction (const ParametricFunction &modelFCN)
	Sets the model function for the data (for example gaussian+linear for a peak) More...

const ParametricFunction *	ModelFunction () const
	Returns the model function used for the data. More...

virtual std::vector< double >	Elements (const std::vector< double > &par) const =0
	Evaluates the model function for the different measurement points and the Parameter values supplied, calculates a figure-of-merit for each measurement and returns a vector containing the result of this evaluation. More...

virtual const std::vector < double > &	GetMeasurement (int Index) const =0
	Accessor to the parameters of a given measurement. More...

virtual int	GetNumberOfMeasurements () const =0
	Accessor to the number of measurements used for calculating the present figure of merit. More...

double	operator() (const std::vector< double > &par) const
	Calculates the sum of Elements squared, ie the chi-square. More...

virtual double	Up () const
	!!!!!!!!!!!! to be commented More...

Public Member Functions inherited from ROOT::Minuit2::FumiliFCNBase
	FumiliFCNBase ()
	Default Constructor. More...

	FumiliFCNBase (unsigned int npar)
	Constructor which initializes the class with the function provided by the user for modeling the data. More...

virtual	~FumiliFCNBase ()

virtual void	EvaluateAll (const std::vector< double > &par)=0
	Evaluate function Value, Gradient and Hessian using Fumili approximation, for values of parameters p The resul is cached inside and is return from the FumiliFCNBase::Value , FumiliFCNBase::Gradient and FumiliFCNBase::Hessian methods. More...

virtual double	Value () const
	Return cached Value of objective function estimated previously using the FumiliFCNBase::EvaluateAll method. More...

virtual const std::vector < double > &	Gradient () const
	Return cached Value of function Gradient estimated previously using the FumiliFCNBase::EvaluateAll method. More...

virtual double	Hessian (unsigned int row, unsigned int col) const
	Return Value of the i-th j-th element of the Hessian matrix estimated previously using the FumiliFCNBase::EvaluateAll method. More...

virtual unsigned int	Dimension ()
	return number of function variable (parameters) , i.e. More...

Public Member Functions inherited from ROOT::Minuit2::FCNBase
virtual	~FCNBase ()

virtual double	ErrorDef () const
	Error definition of the function. More...

virtual void	SetErrorDef (double)
	add interface to set dynamically a new error definition Re-implement this function if needed. More...

Public Member Functions inherited from ROOT::Minuit2::GenericFunction
virtual	~GenericFunction ()

Private Attributes
const ParametricFunction *	fModelFunction

Additional Inherited Members
Protected Member Functions inherited from ROOT::Minuit2::FumiliFCNBase
virtual void	InitAndReset (unsigned int npar)
	initialize and reset values of gradien and Hessian More...

void	SetFCNValue (double value)

std::vector< double > &	Gradient ()

std::vector< double > &	Hessian ()

#include <Minuit2/FumiliChi2FCN.h>

Inheritance diagram for ROOT::Minuit2::FumiliChi2FCN:

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Constructor & Destructor Documentation

ROOT::Minuit2::FumiliChi2FCN::FumiliChi2FCN ( )

inline

Definition at line 56 of file FumiliChi2FCN.h.

virtual ROOT::Minuit2::FumiliChi2FCN::~FumiliChi2FCN ( )

inlinevirtual

Definition at line 58 of file FumiliChi2FCN.h.

Member Function Documentation

virtual std::vector<double> ROOT::Minuit2::FumiliChi2FCN::Elements ( const std::vector< double > & par ) const

pure virtual

Evaluates the model function for the different measurement points and the Parameter values supplied, calculates a figure-of-merit for each measurement and returns a vector containing the result of this evaluation.

Parameters

par	vector of Parameter values to feed to the model function.

Returns: A vector containing the figures-of-merit for the model function evaluated for each set of measurements.

Implemented in ROOT::Minuit2::FumiliStandardChi2FCN.

Referenced by operator()().

virtual const std::vector<double>& ROOT::Minuit2::FumiliChi2FCN::GetMeasurement ( int Index ) const

pure virtual

Accessor to the parameters of a given measurement.

For example in the case of a chi-square fit with a one-dimensional Gaussian, the Parameter characterizing the measurement will be the position. It is the Parameter that is feeded to the model function.

Parameters

Index Index of the measueremnt the parameters of which to return