ROOT::Math::IGradientFunctionMultiDimTempl< T > Class Template Reference

template<class T>
class ROOT::Math::IGradientFunctionMultiDimTempl< T >

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

The method ROOT::Math::IFunction::Gradient calculates the full gradient vector, ROOT::Math::IFunction::Derivative calculates the partial derivative for each coordinate and ROOT::Math::Fdf calculates the gradient and the function value at the same time. The pure private virtual method DoDerivative() must be implemented by the derived classes, while Gradient and FdF are by default implemented using DoDerivative, butthey can be overloaded by the derived classes to improve the efficiency in the derivative calculation.

Gradient interface (abstract class) defining the signature for calculating the gradient of a multi-dimensional function. Three methods are provided:

• Gradient(const double *x, double * grad) evaluate the full gradient vector at the vector value x
• Derivative(const double * x, int icoord) evaluate the partial derivative for the icoord coordinate
• FdF(const double *x, double &f, double * g) evaluate at the same time gradient and function/

Definition at line 252 of file IFunction.h.

Public Member Functions
bool	HasGradient () const override
Public Member Functions inherited from ROOT::Math::IBaseFunctionMultiDimTempl< T >
virtual	~IBaseFunctionMultiDimTempl ()=default
virtual IBaseFunctionMultiDimTempl< T > *	Clone () const =0
	Clone a function.
T	Derivative (const T *x, unsigned int icoord, T *previous_grad, T *previous_g2, T *previous_gstep) const
	In some cases, the derivative algorithm will use information from the previous step, these can be passed in with this overload.
T	Derivative (const T *x, unsigned int icoord=0) const
	Return the partial derivative with respect to the passed coordinate.
virtual void	FdF (const T *x, T &f, T *df) const
	Optimized method to evaluate at the same time the function value and derivative at a point x.
virtual void	Gradient (const T *x, T *grad) const
	Evaluate all the vector of function derivatives (gradient) at a point x.
virtual void	GradientWithPrevResult (const T *x, T *grad, T *previous_grad, T *previous_g2, T *previous_gstep) const
	In some cases, the gradient algorithm will use information from the previous step, these can be passed in with this overload.
virtual unsigned int	NDim () const =0
	Retrieve the dimension of the function.
T	operator() (const T *x) const
	Evaluate the function at a point x[].
virtual bool	returnsInMinuit2ParameterSpace () const

Additional Inherited Members
Public Types inherited from ROOT::Math::IBaseFunctionMultiDimTempl< T >
typedef T	BackendType
typedef IBaseFunctionMultiDimTempl< T >	BaseFunc

#include <Math/IFunction.h>

Inheritance diagram for ROOT::Math::IGradientFunctionMultiDimTempl< T >:

Member Function Documentation

HasGradient()

template<class T >

bool ROOT::Math::IGradientFunctionMultiDimTempl< T >::HasGradient ( ) const

inlineoverridevirtual

Reimplemented from ROOT::Math::IBaseFunctionMultiDimTempl< T >.

Definition at line 256 of file IFunction.h.