User class for performing function integration.

It will use the Gauss-Legendre Method for function integration in a given interval. This class is implemented from TF1::Integral().

Definition at line 39 of file GaussLegendreIntegrator.h.

Public Member Functions
	GaussLegendreIntegrator (int num=10, double eps=1e-12)
	Basic contructor of GaussLegendreIntegrator. More...

virtual	~GaussLegendreIntegrator ()
	Default Destructor. More...

void	SetNumberPoints (int num)
	Set the number of points used in the calculation of the integral. More...

virtual void	SetRelTolerance (double)
	Set the desired relative Error. More...

virtual void	SetAbsTolerance (double)
	This method is not implemented. More...

void	GetWeightVectors (double x, double w) const
	Returns the arrays x and w containing the abscissa and weight of the Gauss-Legendre n-point quadrature formula. More...

int	GetNumberPoints () const

int	NEval () const
	return number of function evaluations in calculating the integral This is equivalent to the number of points More...

virtual ROOT::Math::IntegratorOneDimOptions	Options () const
	get the option used for the integration More...

virtual void	SetOptions (const ROOT::Math::IntegratorOneDimOptions &opt)
	set the options (should be re-implemented by derived classes -if more options than tolerance exist More...

Public Member Functions inherited from ROOT::Math::GaussIntegrator
virtual	~GaussIntegrator ()
	Destructor. More...

	GaussIntegrator (double absTol=-1, double relTol=-1)
	Default Constructor. More...

void	AbsValue (bool flag)
	Static function: set the fgAbsValue flag. More...

double	Result () const
	Returns the result of the last Integral calculation. More...

double	Error () const
	Return the estimate of the absolute Error of the last Integral calculation. More...

int	Status () const
	return the status of the last integration - 0 in case of success More...

double	Integral (double a, double b)
	Returns Integral of function between a and b. More...

double	Integral ()
	Returns Integral of function on an infinite interval. More...

double	IntegralUp (double a)
	Returns Integral of function on an upper semi-infinite interval. More...

double	IntegralLow (double b)
	Returns Integral of function on a lower semi-infinite interval. More...

void	SetFunction (const IGenFunction &)
	Set integration function (flag control if function must be copied inside). More...

double	Integral (const std::vector< double > &pts)
	This method is not implemented. More...

double	IntegralCauchy (double a, double b, double c)
	This method is not implemented. More...

Public Member Functions inherited from ROOT::Math::VirtualIntegratorOneDim
virtual	~VirtualIntegratorOneDim ()
	destructor: no operation More...

virtual ROOT::Math::IntegrationOneDim::Type	Type () const

Public Member Functions inherited from ROOT::Math::VirtualIntegrator
virtual	~VirtualIntegrator ()

Protected Attributes
int	fNum

double *	fX

double *	fW

Protected Attributes inherited from ROOT::Math::GaussIntegrator
double	fEpsRel

double	fEpsAbs

bool	fUsedOnce

double	fLastResult

double	fLastError

const IGenFunction *	fFunction

Private Member Functions
virtual double	DoIntegral (double a, double b, const IGenFunction *func)
	Integration surrugate method. More...

void	CalcGaussLegendreSamplingPoints ()
	Type: unsafe but fast interface filling the arrays x and w (static method) More...

Additional Inherited Members
Static Protected Attributes inherited from ROOT::Math::GaussIntegrator
static bool	fgAbsValue = false

#include <Math/GaussLegendreIntegrator.h>

Inheritance diagram for ROOT::Math::GaussLegendreIntegrator:

Collaboration diagram for ROOT::Math::GaussLegendreIntegrator:

Constructor & Destructor Documentation

ROOT::Math::GaussLegendreIntegrator::GaussLegendreIntegrator	(	int	num = `10`,
		double	eps = `1e-12`
	)

Basic contructor of GaussLegendreIntegrator.

@param num Number of desired points to calculate the integration. @param eps Desired relative error.

Definition at line 19 of file GaussLegendreIntegrator.cxx.

ROOT::Math::GaussLegendreIntegrator::~GaussLegendreIntegrator ( )

virtual

Default Destructor.

Definition at line 30 of file GaussLegendreIntegrator.cxx.

Member Function Documentation

void ROOT::Math::GaussLegendreIntegrator::CalcGaussLegendreSamplingPoints ( )

private

Type: unsafe but fast interface filling the arrays x and w (static method)

Given the number of sampling points this routine fills the arrays x and w of length num, containing the abscissa and weight of the Gauss-Legendre n-point quadrature formula.

Gauss-Legendre: W(x)=1 -1<x<1 (j+1)P_{j+1} = (2j+1)xP_j-jP_{j-1}

num is the number of sampling points (>0) x and w are arrays of size num eps is the relative precision

If num<=0 or eps<=0 no action is done.

Reference: Numerical Recipes in C, Second Edition

Definition at line 94 of file GaussLegendreIntegrator.cxx.

Referenced by GaussLegendreIntegrator(), SetNumberPoints(), SetOptions(), and SetRelTolerance().