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Reference Guide
ROOT::Minuit2::FCNBase Class Referenceabstract

Interface (abstract class) defining the function to be minimized, which has to be implemented by the user.

Author
Fred James and Matthias Winkler; modified by Andras Zsenei and Lorenzo Moneta

Definition at line 47 of file FCNBase.h.

Public Member Functions

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 ()
 

#include <Minuit2/FCNBase.h>

Inheritance diagram for ROOT::Minuit2::FCNBase:
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Constructor & Destructor Documentation

◆ ~FCNBase()

virtual ROOT::Minuit2::FCNBase::~FCNBase ( )
inlinevirtual

Definition at line 52 of file FCNBase.h.

Member Function Documentation

◆ ErrorDef()

virtual double ROOT::Minuit2::FCNBase::ErrorDef ( ) const
inlinevirtual

Error definition of the function.

MINUIT defines Parameter errors as the change in Parameter Value required to change the function Value by up. Normally, for chisquared fits it is 1, and for negative log likelihood, its Value is 0.5. If the user wants instead the 2-sigma errors for chisquared fits, it becomes 4, as Chi2(x+n*sigma) = Chi2(x) + n*n.

Comment a little bit better with links!!!!!!!!!!!!!!!!!

Definition at line 93 of file FCNBase.h.

◆ operator()()

virtual double ROOT::Minuit2::FCNBase::operator() ( const std::vector< double > &  x) const
pure virtual

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.

The order and the position of these parameters is strictly the one specified by the user when supplying the starting values for minimization. The starting values must be specified by the user, either via an std::vector<double> or the MnUserParameters supplied as input to the MINUIT minimizers such as VariableMetricMinimizer or MnMigrad. Later values are determined by MINUIT as it searches for the Minimum or performs whatever analysis is requested by the user.

Parameters
parfunction parameters as defined by the user.
Returns
the Value of the function.
See also
MnUserParameters
VariableMetricMinimizer
MnMigrad

Implements ROOT::Minuit2::GenericFunction.

Implemented in ROOT::Minuit2::FumiliChi2FCN, ROOT::Minuit2::FumiliMaximumLikelihoodFCN, ROOT::Minuit2::ParametricFunction, ROOT::Minuit2::FumiliFCNAdapter< Function >, ROOT::Minuit2::FCNGradAdapter< Function >, and ROOT::Minuit2::FCNAdapter< Function >.

◆ SetErrorDef()

virtual void ROOT::Minuit2::FCNBase::SetErrorDef ( double  )
inlinevirtual

add interface to set dynamically a new error definition Re-implement this function if needed.

Reimplemented in ROOT::Minuit2::FumiliFCNAdapter< Function >, and ROOT::Minuit2::FCNAdapter< Function >.

Definition at line 114 of file FCNBase.h.

◆ Up()

virtual double ROOT::Minuit2::FCNBase::Up ( ) const
pure virtual

Error definition of the function.

MINUIT defines Parameter errors as the change in Parameter Value required to change the function Value by up. Normally, for chisquared fits it is 1, and for negative log likelihood, its Value is 0.5. If the user wants instead the 2-sigma errors for chisquared fits, it becomes 4, as Chi2(x+n*sigma) = Chi2(x) + n*n.

Implemented in ROOT::Minuit2::FumiliMaximumLikelihoodFCN, ROOT::Minuit2::FumiliChi2FCN, ROOT::Minuit2::FumiliFCNAdapter< Function >, ROOT::Minuit2::FCNGradAdapter< Function >, and ROOT::Minuit2::FCNAdapter< Function >.

Libraries for ROOT::Minuit2::FCNBase:
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The documentation for this class was generated from the following file: