class ROOT::Math::Derivator


    Class for computing numerical derivative of a function.
    Presently this class is implemented only using the numerical derivatives
    algorithms provided by GSL
    using the implementation class ROOT::Math::GSLDerivator

    This class does not support copying

    @ingroup Deriv

Function Members (Methods)

public:

virtual	~Derivator()
ROOT::Math::Derivator	Derivator()
ROOT::Math::Derivator	Derivator(const ROOT::Math::IGenFunction& f)
ROOT::Math::Derivator	Derivator(const ROOT::Math::Derivator::GSLFuncPointer& f, void* p = 0)
double	Error() const
double	Eval(double x, double h = 1.0E-8) const
static double	Eval(const ROOT::Math::IGenFunction& f, double x, double h = 1.0E-8)
static double	Eval(const ROOT::Math::IMultiGenFunction& f, const double* x, unsigned int icoord = 0, double h = 1.0E-8)
static double	Eval(ROOT::Math::IParamFunction& f, double x, const double* p, unsigned int ipar = 0, double h = 1.0E-8)
static double	Eval(ROOT::Math::IParamMultiFunction& f, const double* x, const double* p, unsigned int ipar = 0, double h = 1.0E-8)
double	EvalBackward(double x, double h = 1.0E-8) const
static double	EvalBackward(const ROOT::Math::IGenFunction& f, double x, double h = 1.0E-8)
double	EvalCentral(double x, double h = 1.0E-8) const
static double	EvalCentral(const ROOT::Math::IGenFunction& f, double x, double h = 1.0E-8)
double	EvalForward(double x, double h = 1.0E-8) const
static double	EvalForward(const ROOT::Math::IGenFunction& f, double x, double h = 1.0E-8)
double	Result() const
void	SetFunction(const ROOT::Math::IGenFunction& f)
void	SetFunction(const ROOT::Math::Derivator::GSLFuncPointer& f, void* p = 0)
int	Status() const

private:

ROOT::Math::Derivator	Derivator(const ROOT::Math::Derivator&)
ROOT::Math::Derivator&	operator=(const ROOT::Math::Derivator&)

Data Members

private:

ROOT::Math::GSLDerivator*	fDerivator

Class Charts

Inheritance Inherited Members Includes Libraries

Function documentation

Derivator()

      Empty Construct for a Derivator class
      Need to set the function afterwards with Derivator::SetFunction

explicit Derivator(const IGenFunction &f)

      Construct using a ROOT::Math::IGenFunction interface

explicit Derivator(const ROOT::Math::Derivator::GSLFuncPointer& f, void* p = 0)

      Construct using a GSL function pointer type
       @param f :  free function pointer of the GSL required type
       @param p :  pointer to the object carrying the function state
                    (for example the function object itself)

virtual ~Derivator()

 destructor

Derivator(const Derivator &)

 disable copying

void SetFunction(const ROOT::Math::IGenFunction& f)

       Template methods for generic functions
       Set the function f for evaluating the derivative.
       The function type must implement the assigment operator,
       <em>  double  operator() (  double  x ) </em>

SetFunction(const ROOT::Math::Derivator::GSLFuncPointer& f, void* p = 0)

double Eval(double x, double h = 1.0E-8) const

       Computes the numerical derivative of a function f at a point x.
       It uses Derivator::EvalCentral to compute the derivative using an
       adaptive central difference algorithm with a step size h

double EvalCentral(double x, double h = 1.0E-8) const

       Computes the numerical derivative at a point x using an adaptive central
       difference algorithm with a step size h.

double EvalForward(double x, double h = 1.0E-8) const

       Computes the numerical derivative at a point x using an adaptive forward
       difference algorithm with a step size h.
       The function is evaluated only at points greater than x and at x itself.

double EvalBackward(double x, double h = 1.0E-8) const

       Computes the numerical derivative at a point x using an adaptive backward
       difference algorithm with a step size h.
       The function is evaluated only at points less than x and at x itself.

double Eval(const ROOT::Math::IGenFunction& f, double x, double h = 1.0E-8)

 @name --- Static methods ---
       This methods don't require to use a Derivator object, and are designed to be used in
       fast calculation. Error and status code cannot be retrieved in this case


       Computes the numerical derivative of a function f at a point x.
       It uses Derivator::EvalCentral to compute the derivative using an
       adaptive central difference algorithm with a step size h

double EvalCentral(const ROOT::Math::IGenFunction& f, double x, double h = 1.0E-8)

       Computes the numerical derivative of a function f at a point x using an adaptive central
       difference algorithm with a step size h

double EvalForward(const ROOT::Math::IGenFunction& f, double x, double h = 1.0E-8)

       Computes the numerical derivative of a function f at a point x using an adaptive forward
       difference algorithm with a step size h.
       The function is evaluated only at points greater than x and at x itself

double EvalBackward(const ROOT::Math::IGenFunction& f, double x, double h = 1.0E-8)

       Computes the numerical derivative of a function f at a point x using an adaptive backward
       difference algorithm with a step size h.
       The function is evaluated only at points less than x and at x itself

double Eval(const ROOT::Math::IMultiGenFunction& f, const double* x, unsigned int icoord = 0, double h = 1.0E-8)

 Derivatives for multi-dimension functions

      Evaluate the partial derivative of a multi-dim function
      with respect coordinate x_icoord at the point x[]

double Eval(ROOT::Math::IParamFunction& f, double x, const double* p, unsigned int ipar = 0, double h = 1.0E-8)

      Evaluate the derivative with respect a parameter for one-dim parameteric function
      at the point ( x,p[]) with respect the parameter p_ipar

double Eval(ROOT::Math::IParamMultiFunction& f, const double* x, const double* p, unsigned int ipar = 0, double h = 1.0E-8)

      Evaluate the derivative with respect a parameter for a multi-dim parameteric function
      at the point ( x[],p[]) with respect the parameter p_ipar

int Status() const

      return the error status of the last derivative calculation

double Result() const

      return  the result of the last derivative calculation

double Error() const

      return the estimate of the absolute error of the last derivative calculation