class ROOT::Math::GSLRandomEngine

Base class for all GSL random engines,
normally user instantiate the derived classes
which creates internally the generator.

The main GSL generators (see
<A HREF="">
here</A>) are available as derived classes
In addition to generate uniform numbers it provides method for
generating numbers according to pre-defined distributions
using the GSL functions from
<A HREF="">
GSL random number distributions</A>.

@ingroup Random

Function Members (Methods)

unsigned intBinomial(double p, unsigned int n) const
doubleCauchy(double a) const
doubleChiSquare(double nu) const
voidDir2D(double& x, double& y) const
voidDir3D(double& x, double& y, double& z) const
doubleExponential(double mu) const
doubleFDist(double nu1, double nu2) const
doubleGamma(double a, double b) const
doubleGaussian(double sigma) const
voidGaussian2D(double sigmaX, double sigmaY, double rho, double& x, double& y) const
doubleGaussianRatio(double sigma) const
doubleGaussianTail(double a, double sigma) const
doubleGaussianZig(double sigma) const
ROOT::Math::GSLRandomEngineGSLRandomEngine(ROOT::Math::GSLRngWrapper* rng)
ROOT::Math::GSLRandomEngineGSLRandomEngine(const ROOT::Math::GSLRandomEngine&)
doubleLandau() const
doubleLogNormal(double zeta, double sigma) const
vector<unsigned int>Multinomial(unsigned int ntot, const vector<double>& p) const
stringName() const
doubleoperator()() const
ROOT::Math::GSLRandomEngine&operator=(const ROOT::Math::GSLRandomEngine&)
unsigned intPoisson(double mu) const
voidRandomArray(double* begin, double* end) const
unsigned intRndmInt(unsigned int max) const
voidSetSeed(unsigned int seed) const
unsigned intSize() const
doubletDist(double nu) const

Data Members

unsigned intfCurTimecurrent time used to seed the generator
ROOT::Math::GSLRngWrapper*fRngpointer to GSL generator wrapper

Class Charts

Inheritance Inherited Members Includes Libraries
Class Charts

Function documentation

default constructor. No creation of rng is done.
If then Initialize() is called an engine is created
based on default GSL type (MT)

GSLRandomEngine( GSLRngWrapper * rng)
create from an existing rng.
User manage the rng pointer which is then deleted olny by calling Terminate()

void Initialize()
initialize the generator
If no rng is present the default one based on Mersenne and Twister is created

void Terminate()
delete pointer to contained rng

virtual ~GSLRandomEngine()
no operation, rng is delete in Terminate()

double operator()()
Generate a  random number between ]0,1]
0 is excluded and 1 is included

unsigned int RndmInt(unsigned int max) const
Generate an integer number between [0,max-1] (including 0 and max-1)
if max is larger than available range of algorithm
an error message is printed and zero is returned

void RandomArray(double* begin, double* end) const
Generate an array of random numbers.
The iterators points to the random numbers

std::string Name()
eturn name of generato

unsigned int Size()
eturn the state size of generato

void SetSeed(unsigned int seed) const
set the random generator seed

double Gaussian(double sigma) const
 @name Random Distributions
Implemented using the
<A HREF="">
GSL Random number Distributions</A>


Gaussian distribution - default method is Box-Muller (polar method)

double GaussianZig(double sigma) const
Gaussian distribution - Ziggurat method

double GaussianRatio(double sigma) const
Gaussian distribution - Ratio method

double GaussianTail(double a, double sigma) const
void Gaussian2D(double sigmaX, double sigmaY, double rho, double& x, double& y) const
Bivariate Gaussian distribution with correlation

double Exponential(double mu) const
Exponential distribution

double Cauchy(double a) const
Cauchy distribution

double Landau()
Landau distribution

double Gamma(double a, double b) const
Gamma distribution

double LogNormal(double zeta, double sigma) const
Log Normal distribution

double ChiSquare(double nu) const
Chi square distribution

double FDist(double nu1, double nu2) const
F distrbution

double tDist(double nu) const
t student distribution

void Dir2D(double& x, double& y) const
generate random numbers in a 2D circle of radious 1

void Dir3D(double& x, double& y, double& z) const
generate random numbers in a 3D sphere of radious 1

unsigned int Poisson(double mu) const
Poisson distribution

unsigned int Binomial(double p, unsigned int n) const
Binomial distribution

std::vector<unsigned int> Multinomial(unsigned int ntot, const vector<double>& p) const
Multinomial distribution

Author: L. Moneta, A. Zsenei 08/2005
Last update: root/mathmore:$Id: GSLRndmEngines.h 21553 2007-12-21 10:55:46Z moneta $
Copyright (c) 2004 ROOT Foundation, CERN/PH-SFT *

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