ROOT 6.08/07 Reference Guide 
Interface (abstract class) for multidimensional functions providing a gradient calculation.
It implements both the ROOT::Math::IBaseFunctionMultiDim and ROOT::Math::IGradientMultiDim interfaces. 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.
Definition at line 322 of file IFunction.h.
Public Types  
typedef IBaseFunctionMultiDim  BaseFunc 
typedef IGradientMultiDim  BaseGrad 
Public Types inherited from ROOT::Math::IBaseFunctionMultiDim  
typedef IBaseFunctionMultiDim  BaseFunc 
Public Member Functions  
virtual  ~IGradientFunctionMultiDim () 
Virtual Destructor (no operations) More...  
virtual void  FdF (const double *x, double &f, double *df) const 
Optimized method to evaluate at the same time the function value and derivative at a point x. More...  
virtual void  Gradient (const double *x, double *grad) const 
Evaluate all the vector of function derivatives (gradient) at a point x. More...  
Public Member Functions inherited from ROOT::Math::IBaseFunctionMultiDim  
IBaseFunctionMultiDim ()  
virtual  ~IBaseFunctionMultiDim () 
virtual destructor More...  
virtual IBaseFunctionMultiDim *  Clone () const =0 
Clone a function. More...  
virtual unsigned int  NDim () const =0 
Retrieve the dimension of the function. More...  
double  operator() (const double *x) const 
Evaluate the function at a point x[]. More...  
Public Member Functions inherited from ROOT::Math::IGradientMultiDim  
virtual  ~IGradientMultiDim () 
virual destructor More...  
double  Derivative (const double *x, unsigned int icoord=0) const 
Return the partial derivative with respect to the passed coordinate. More...  
#include <Math/IFunction.h>
Definition at line 329 of file IFunction.h.
Definition at line 330 of file IFunction.h.

inlinevirtual 
Virtual Destructor (no operations)
Definition at line 336 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::IGradientMultiDim.
Reimplemented in ROOT::Math::LSResidualFunc, and TPyMultiGradFunction.
Definition at line 358 of file IFunction.h.

inlinevirtual 
Evaluate all the vector of function derivatives (gradient) at a point x.
Derived classes must reimplement it if more efficient than evaluting one at a time
Implements ROOT::Math::IGradientMultiDim.
Reimplemented in ROOT::Math::LSResidualFunc, and TPyMultiGradFunction.
Definition at line 342 of file IFunction.h.