 ROOT   Reference Guide
Searching...
No Matches

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

It implements both the ROOT::Math::IBaseFunctionOneDim and ROOT::Math::IGradientOneDim interfaces. 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.

Definition at line 381 of file IFunction.h.

## Public Types

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

## Public Member Functions

Virtual Destructor (no operations)

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. Public Member Functions inherited from ROOT::Math::IBaseFunctionOneDim
IBaseFunctionOneDim ()

virtual ~IBaseFunctionOneDim ()
virtual destructor

virtual IBaseFunctionOneDimClone () const =0
Clone a function.

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

double operator() (double x) const
Evaluate the function at a point x Use the a pure virtual private method DoEval which must be implemented by sub-classes. Public Member Functions inherited from ROOT::Math::IGradientOneDim
virtual destructor

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

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

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

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

#include <Math/IFunction.h>

[legend]

## ◆ BaseFunc

Definition at line 388 of file IFunction.h.

Definition at line 389 of file IFunction.h.

## Constructor & Destructor Documentation

inlinevirtual

Virtual Destructor (no operations)

Definition at line 395 of file IFunction.h.

## ◆ FdF()

 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 