Random number generator class. More...

#include <GRan.hpp>

Inheritance diagram for GRan:

Public Member Functions
	GRan (void)
	Void constructor. More...

	GRan (unsigned long long int seed)
	Seed constructor. More...

	GRan (const GRan &ran)
	Copy constructor. More...

virtual	~GRan (void)
	Destructor. More...

GRan &	operator= (const GRan &ran)
	Assignment operator. More...

void	clear (void)
	Clear random number generator. More...

GRan *	clone (void) const
	Clone random number generator. More...

std::string	classname (void) const
	Return class name. More...

void	seed (unsigned long long int seed)
	Set seed of random number generator. More...

unsigned long long int	seed (void) const
	Return seed value. More...

unsigned long int	int32 (void)
	Return 32-bit random unsigned integer. More...

unsigned long long int	int64 (void)
	Return 64-bit random unsigned integer. More...

double	uniform (void)
	Returns random double precision floating value in range 0 to 1. More...

double	normal (void)
	Returns normal deviates. More...

double	exp (const double &lambda)
	Returns exponential deviates. More...

double	poisson (const double &lambda)
	Returns Poisson deviates. More...

double	chisq2 (void)
	Returns Chi2 deviates for 2 degrees of freedom. More...

int	cdf (const std::vector< double > &cdf)
	Random sampling from a cumulative density function. More...

int	cdf (const GVector &cdf)
	Random sampling from a cumulative density function. More...

std::string	print (const GChatter &chatter=NORMAL) const
	Print random number generator information. More...

Public Member Functions inherited from GBase
virtual	~GBase (void)
	Destructor. More...

Protected Member Functions
void	init_members (unsigned long long int seed=41L)
	Initialise class members. More...

void	copy_members (const GRan &ran)
	Copy class members. More...

void	free_members (void)
	Delete class members. More...

Protected Attributes
unsigned long long int	m_seed
	Random number generator seed. More...

unsigned long long int	m_value1
	Value 1. More...

unsigned long long int	m_value2
	Value 2. More...

unsigned long long int	m_value3
	Value 3. More...

double	m_old_lambda
	Old lambda value. More...

double	m_sqrt_lambda
	sqrt(2*lambda) More...

double	m_log_lambda
	log(lambda) More...

double	m_exp_lambda
	exp(-lambda) More...

Detailed Description

Random number generator class.

This class implements a random number generator.

Definition at line 44 of file GRan.hpp.

Constructor & Destructor Documentation

GRan::GRan ( void )

Void constructor.

Definition at line 57 of file GRan.cpp.

References init_members().

Referenced by clone().

GRan::GRan ( unsigned long long int seed )

Seed constructor.

Parameters

[in] seed Random number generator seed.

Definition at line 72 of file GRan.cpp.

References init_members().

GRan::GRan ( const GRan & ran )

Copy constructor.

Parameters

[in] ran Random number generator.

Definition at line 87 of file GRan.cpp.

References copy_members(), and init_members().

GRan::~GRan ( void )

virtual

Destructor.

Definition at line 103 of file GRan.cpp.

References free_members().

Member Function Documentation

int GRan::cdf ( const std::vector< double > & cdf )

Random sampling from a cumulative density function.

Parameters

[in] cdf Array containing cumulative density function

Definition at line 390 of file GRan.cpp.

References uniform().

int GRan::cdf ( const GVector & cdf )

Random sampling from a cumulative density function.

Parameters

[in] cdf Vector containing cumulative density function

Todo:: Somehow merge with the above method to reduce code repetition

Definition at line 421 of file GRan.cpp.

References GVector::size(), and uniform().

double GRan::chisq2 ( void )

Returns Chi2 deviates for 2 degrees of freedom.

Returns exponential deviates from the probability distribution

\[p(x) = \frac{1}{2\pi} x \exp( -\frac{1}{2} x^2 )\]

This method can be used to simulate the random radial offset of a measured source position from the true source position, assuming an azimuthally symmetric 2D Gaussian probability distribution.

Definition at line 370 of file GRan.cpp.

References log(), sqrt(), and uniform().

Referenced by GCTAPsfPerfTable::mc(), GCTAPsfVector::mc(), GModelSpatialRadialGauss::mc(), and GCTAPsf2D::mc().

std::string GRan::classname ( void ) const

inlinevirtual

Return class name.

Returns: String containing the class name ("GRan").

Implements GBase.

Definition at line 99 of file GRan.hpp.

void GRan::clear ( void )

virtual

Clear random number generator.

This method properly resets the object to an initial state using the default seed.

Implements GBase.

Definition at line 158 of file GRan.cpp.

References free_members(), and init_members().

GRan * GRan::clone ( void ) const

virtual

Clone random number generator.

Returns: Pointer to deep copy of random number generator.

Implements GBase.

Definition at line 176 of file GRan.cpp.

References GRan().

void GRan::copy_members ( const GRan & ran )

protected

Copy class members.

Parameters

[in] ran Random number generator.

Definition at line 513 of file GRan.cpp.

References m_exp_lambda, m_log_lambda, m_old_lambda, m_seed, m_sqrt_lambda, m_value1, m_value2, and m_value3.

Referenced by GRan(), and operator=().

double GRan::exp ( const double & lambda )

Returns exponential deviates.

Parameters

[in] lambda Mean rate.

Returns exponential deviates from the probability distribution

\[p(x) = \lambda \exp( -\lambda x )\]

where \(\lambda\) is the parameter of the distribution. This method may be used to simulate the occurence time of an event, where \(\lambda\) is the mean event rate. Convsersely, \(1/\lambda\) is the mean waiting time between events.