ROOT   6.08/07 Reference Guide

## Public Member Functions

std::vector< double > Gradient (const std::vector< double > &v) const

double operator() (const std::vector< double > &v) const
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...

double operator() (const double *v) const

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

Public Member Functions inherited from ROOT::Minuit2::FCNGradientBase

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 Function & fFunc

double fUp

#include <Minuit2/FCNGradAdapter.h>

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## Constructor & Destructor Documentation

template<class Function>
 ROOT::Minuit2::FCNGradAdapter< Function >::FCNGradAdapter ( const Function & f, double up = 1. )
inline

template<class Function>
inline

## Member Function Documentation

template<class Function>
inlinevirtual

template<class Function>
inlinevirtual

## ◆ operator()() [1/2]

template<class Function>
 double ROOT::Minuit2::FCNGradAdapter< Function >::operator() ( const std::vector< double > & x ) const
inlinevirtual

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
 par function parameters as defined by the user.
Returns
the Value of the function.
MnUserParameters
VariableMetricMinimizer

Implements ROOT::Minuit2::FCNBase.

## ◆ operator()() [2/2]

template<class Function>
inline

## ◆ Up()

template<class Function>
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.

Implements ROOT::Minuit2::FCNBase.

## ◆ fFunc

template<class Function>
private

template<class Function>
mutableprivate