Interface (abstract class) for onedimensional 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 
typedef IGradientOneDim  BaseGrad 
Public Types inherited from ROOT::Math::IBaseFunctionOneDim  
typedef IBaseFunctionOneDim  BaseFunc 
Public Member Functions  
virtual  ~IGradientFunctionOneDim () 
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 IBaseFunctionOneDim *  Clone () 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 subclasses.  
Public Member Functions inherited from ROOT::Math::IGradientOneDim  
virtual  ~IGradientOneDim () 
virtual destructor  
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.  
void  Gradient (const double *x, double *g) const 
Compatibility method with multidimensional interface for Gradient.  
#include <Math/IFunction.h>
Definition at line 388 of file IFunction.h.
Definition at line 389 of file IFunction.h.

inlinevirtual 
Virtual Destructor (no operations)
Definition at line 395 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
Implements ROOT::Math::IGradientOneDim.
Definition at line 405 of file IFunction.h.