ROOT   Reference Guide

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.

Concrete classes should derive from ROOT::Math::IGradientFunctionOneDim and not from this class.

Definition at line 247 of file IFunction.h.

## Public Member Functions

virtual destructor More...

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 =0
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...

## Private Member Functions

virtual double DoDerivative (double x) const =0
function to evaluate the derivative with respect each coordinate. More...

#include <Math/IFunction.h>

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## Constructor & Destructor Documentation

inlinevirtual

virtual destructor

Definition at line 252 of file IFunction.h.

## ◆ Derivative() [1/2]

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

Compatibility method with multi-dimensional interface for partial derivative.

Definition at line 277 of file IFunction.h.

## ◆ Derivative() [2/2]

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

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

Definition at line 258 of file IFunction.h.

## ◆ DoDerivative()

 virtual double ROOT::Math::IGradientOneDim::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::WrappedTF1, ROOT::Math::GradFunctor1D, and ROOT::Math::Polynomial.

## ◆ FdF() [1/2]

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

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

Definition at line 293 of file IFunction.h.

## ◆ FdF() [2/2]

 virtual void ROOT::Math::IGradientOneDim::FdF ( double x, double & f, double & df ) const
pure virtual

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

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