ROOT   Reference Guide

Interface (abstract class) for one-dimensional functions providing a gradient calculation.

The method ROOT::Math::IFunction::Derivative calculates the derivative and ROOT::Math::Fdf calculates the derivative and the function values at the same time. The pure private virtual method DoDerivative() must be implemented by the derived classes, while FdF is by default implemented using DoDerivative, but it can be overloaded by the derived classes to improve the efficiency in the derivative calculation.

Specialized Gradient interface(abstract class) for one dimensional functions It provides a method to evaluate the derivative of the function, Derivative and a method to evaluate at the same time the function and the derivative FdF

Definition at line 254 of file IFunction.h.

## Public Types

typedef IBaseFunctionOneDim BaseFunc

Public Types inherited from ROOT::Math::IBaseFunctionOneDim
typedef IBaseFunctionOneDim BaseFunc

## Public Member Functions

double Derivative (const double *x) const
Compatibility method with multi-dimensional interface for partial derivative. More...

double Derivative (double x) const
Return the derivative of the function at a point x Use the private method DoDerivative. More...

void FdF (const double *x, double &f, double *df) const
Compatibility method with multi-dimensional interface for Gradient and function evaluation. More...

virtual void FdF (double x, double &f, double &df) const
Optimized method to evaluate at the same time the function value and derivative at a point x. More...

void Gradient (const double *x, double *g) const
Compatibility method with multi-dimensional interface for Gradient. More...

Public Member Functions inherited from ROOT::Math::IBaseFunctionOneDim
virtual ~IBaseFunctionOneDim ()=default

virtual IBaseFunctionOneDimClone () const =0
Clone a function. More...

double operator() (const double *x) const
Evaluate the function at a point x[]. More...

double operator() (double x) const
Evaluate the function at a point x. More...

## Private Member Functions

virtual double DoDerivative (double x) const =0
Function to evaluate the derivative with respect each coordinate. To be implemented by the derived class. More...

#include <Math/IFunction.h>

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## ◆ BaseFunc

Definition at line 258 of file IFunction.h.

Definition at line 259 of file IFunction.h.

## ◆ Derivative() [1/2]

 double ROOT::Math::IGradientFunctionOneDim::Derivative ( const double * x ) const
inline

Compatibility method with multi-dimensional interface for partial derivative.

Definition at line 266 of file IFunction.h.

## ◆ Derivative() [2/2]

 double ROOT::Math::IGradientFunctionOneDim::Derivative ( double x ) const
inline

Return the derivative of the function at a point x Use the private method DoDerivative.

Definition at line 263 of file IFunction.h.

## ◆ DoDerivative()

 virtual double ROOT::Math::IGradientFunctionOneDim::DoDerivative ( double x ) const
privatepure virtual

Function to evaluate the derivative with respect each coordinate. To be implemented by the derived class.

Implemented in ROOT::Math::GradFunctor1D, ROOT::Math::WrappedTF1, and ROOT::Math::Polynomial.

## ◆ FdF() [1/2]

 void ROOT::Math::IGradientFunctionOneDim::FdF ( const double * x, double & f, double * df ) const
inline

Compatibility method with multi-dimensional interface for Gradient and function evaluation.

Definition at line 282 of file IFunction.h.

## ◆ FdF() [2/2]

 virtual void ROOT::Math::IGradientFunctionOneDim::FdF ( double x, double & f, double & df ) const
inlinevirtual

Optimized method to evaluate at the same time the function value and derivative at a point x.

Often both value and derivatives are needed and it is often more efficient to compute them at the same time. Derived class should implement this method if performances play an important role and if it is faster to evaluate value and derivative at the same time.

Reimplemented in ROOT::Math::WrappedTF1, and ROOT::Math::Polynomial.

Definition at line 275 of file IFunction.h.

 void ROOT::Math::IGradientFunctionOneDim::Gradient ( const double * x, double * g ) const
inline

Compatibility method with multi-dimensional interface for Gradient.

Definition at line 269 of file IFunction.h.

inlineoverridevirtual

Reimplemented from ROOT::Math::IBaseFunctionOneDim.

Definition at line 284 of file IFunction.h.