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 ()

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...

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

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

void	SetModelFunction (const ParametricFunction &modelFCN)
	Sets the model function for the data (for example gaussian+linear for a peak) 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 unsigned int	Dimension ()
	return number of function variable (parameters) , i.e. More...

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

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

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

virtual double	operator() (const std::vector< double > &x) const =0
	The meaning of the vector of parameters is of course defined by the user, who uses the values of those parameters to calculate their function Value. More...

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

virtual double	Up () const =0
	Error definition of the function. More...

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

virtual double	operator() (const std::vector< double > &x) const =0
	Evaluates the function using the vector containing the input values. More...

Private Attributes
const ParametricFunction *	fModelFunction = nullptr

Additional Inherited Members
Protected Member Functions inherited from ROOT::Minuit2::FumiliFCNBase
std::vector< double > &	Gradient ()

std::vector< double > &	Hessian ()

virtual void	InitAndReset (unsigned int npar)
	initialize and reset values of gradien and Hessian More...

void	SetFCNValue (double value)

#include <Minuit2/FumiliChi2FCN.h>

Inheritance diagram for ROOT::Minuit2::FumiliChi2FCN:

[legend]

Constructor & Destructor Documentation

◆ FumiliChi2FCN()

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

inline

Definition at line 56 of file FumiliChi2FCN.h.

◆ ~FumiliChi2FCN()

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

inlinevirtual

Definition at line 58 of file FumiliChi2FCN.h.

Member Function Documentation

◆ Elements()

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.

◆ GetMeasurement()

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

Returns: A reference to a vector containing the values characterizing a measurement

Implemented in ROOT::Minuit2::FumiliStandardChi2FCN.

◆ GetNumberOfMeasurements()

virtual int ROOT::Minuit2::FumiliChi2FCN::GetNumberOfMeasurements ( ) const

pure virtual

Accessor to the number of measurements used for calculating the present figure of merit.

Returns: the number of measurements

Implemented in ROOT::Minuit2::FumiliStandardChi2FCN.

◆ ModelFunction()

const ParametricFunction * ROOT::Minuit2::FumiliChi2FCN::ModelFunction ( ) const

inline

Returns the model function used for the data.

Returns: Returns a pointer to the model function.

Definition at line 81 of file FumiliChi2FCN.h.

◆ operator()()

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

inlinevirtual

Calculates the sum of Elements squared, ie the chi-square.

The user must implement in a class which inherits from FumiliChi2FCN the member function Elements() which will supply the Elements for the sum.

Parameters

par	vector containing the Parameter values for the model function

Returns: The sum of Elements squared

See also: FumiliFCNBase::elements

Implements ROOT::Minuit2::FCNBase.

Definition at line 146 of file FumiliChi2FCN.h.

◆ SetModelFunction()

void ROOT::Minuit2::FumiliChi2FCN::SetModelFunction ( const ParametricFunction & modelFCN )

inline

Sets the model function for the data (for example gaussian+linear for a peak)

Parameters

modelFunction a reference to the model function.

Definition at line 69 of file FumiliChi2FCN.h.

◆ Up()

virtual double ROOT::Minuit2::FumiliChi2FCN::Up ( ) const

inlinevirtual

!!!!!!!!!!!! to be commented

Implements ROOT::Minuit2::FCNBase.

Definition at line 166 of file FumiliChi2FCN.h.

Member Data Documentation

◆ fModelFunction

const ParametricFunction* ROOT::Minuit2::FumiliChi2FCN::fModelFunction = nullptr

private

Definition at line 171 of file FumiliChi2FCN.h.

Libraries for ROOT::Minuit2::FumiliChi2FCN:

[legend]

Public Member Functions

Private Attributes

Additional Inherited Members

Constructor & Destructor Documentation

◆ FumiliChi2FCN()

◆ ~FumiliChi2FCN()

Member Function Documentation

◆ Elements()

◆ GetMeasurement()

◆ GetNumberOfMeasurements()

◆ ModelFunction()

◆ operator()()

◆ SetModelFunction()

◆ Up()

Member Data Documentation

◆ fModelFunction