Interface (abstract class) for onedimensional 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 
typedef IGradientFunctionOneDim  BaseGrad 
Public Types inherited from ROOT::Math::IBaseFunctionOneDim  
typedef IBaseFunctionOneDim  BaseFunc 
Public Member Functions  
double  Derivative (const double *x) const 
Compatibility method with multidimensional 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 multidimensional interface for Gradient and function evaluation.  
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.  
void  Gradient (const double *x, double *g) const 
Compatibility method with multidimensional interface for Gradient.  
bool  HasGradient () const override 
Public Member Functions inherited from ROOT::Math::IBaseFunctionOneDim  
virtual  ~IBaseFunctionOneDim ()=default 
virtual IBaseFunctionOneDim *  Clone () const =0 
Clone a function.  
virtual bool  HasGradient () const 
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.  
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.  
#include <Math/IFunction.h>
Definition at line 258 of file IFunction.h.
Definition at line 259 of file IFunction.h.
Compatibility method with multidimensional interface for partial derivative.
Definition at line 266 of file IFunction.h.
Return the derivative of the function at a point x Use the private method DoDerivative.
Definition at line 263 of file IFunction.h.

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.

inline 
Compatibility method with multidimensional interface for Gradient and function evaluation.
Definition at line 282 of file IFunction.h.

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.
Compatibility method with multidimensional 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.