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 37 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...

int	GetNumberPoints () const

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

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

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

Public Member Functions inherited from ROOT::Math::GaussIntegrator
	GaussIntegrator (double absTol=-1, double relTol=-1)
	Default Constructor. More...

virtual	~GaussIntegrator ()
	Destructor. More...

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

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

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

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

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

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

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

double *	fX

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

double	fEpsRel

const IGenFunction *	fFunction

double	fLastError

double	fLastResult

bool	fUsedOnce

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

virtual double	DoIntegral (double a, double b, const IGenFunction *func)
	Integration surrugate 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:

[legend]

Constructor & Destructor Documentation

◆ GaussLegendreIntegrator()

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 23 of file GaussLegendreIntegrator.cxx.

◆ ~GaussLegendreIntegrator()

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

virtual

Default Destructor.

Definition at line 34 of file GaussLegendreIntegrator.cxx.

Member Function Documentation

◆ CalcGaussLegendreSamplingPoints()

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 98 of file GaussLegendreIntegrator.cxx.