#include <itkNormalVariateGenerator.h>

Detailed Description

Normal random variate generator.

This generation method was initially developed and implemented by Martin Styner, University of North Carolina at Chapel Hill, and his colleagues.

You should run Initialize() function before call GetNormalVariate() function.

The following are original comments.

Revision date 31 May 1996 This is a revised version of the algorithm described in

ACM Transactions on Mathematical Software, Vol 22, No 1 March 1996, pp 119-127.

It is somewhat faster, and uses less memory as the vector of variates is updated in-situ. It has passed all the same statistical tests as described in the TOMS article, plus others. Seems OK so far.

   Works well with total pool of 1024 variates, and does not need
   two vectors of this size, so does less damage to cache.
           Has been tested for frequency of tail values which
   should occur once in a million. OK. Other usual tests OK.
   About 13 % faster than TOMS version.

   FAST GENERATOR OF PSEUDO-RANDOM UNIT NORMAL VARIATES

           C.S.Wallace, Monash University, 1994

To use this code, files needing to call the generator should include:

#include "FastNorm.h"

and be linked with the math library (-lm) FastNorm.h contains declaration of the initialization routine 'initnorm()', definition of a macro 'FastGauss' used to generate variates, and three variables used in the macro. Read below for calling conventions.

THIS CODE ASSUMES TWO'S-COMPLEMENT 32-BIT INTEGER ARITHMETIC. IT ALSO ASSUMES THE 'C' COMPILER COMPILES THE LEFT-SHIFT OPERATOR "<<" AS A LOGICAL SHIFT, DISCARDING THE SIGN DIGIT AND SHIFTING IN ZEROS ON THE RIGHT, SO " X << 1" IS EQUIVALENT TO " X+X ". IT ALSO ASSUMES THE RIGHT-SHIFT OPERATOR ">>" IS SIGN-PRESERVING, SO ( -2 >> 1) = -1, ( -1>>1) = -1.

    A fast generator of pseudo-random variates from the unit Normal

distribution. It keeps a pool of about 1000 variates, and generates new ones by picking 4 from the pool, rotating the 4-vector with these as its components, and replacing the old variates with the components of the rotated vector.

    The program should initialize the generator by calling

initnorm(seed) with seed a int integer seed value. Different seed values will give different sequences of Normals. Then, wherever the program needs a new Normal variate, it should use the macro FastGauss, e.g. in statements like: x = FastGauss; (Sets x to a random Normal value)

Examples: Examples/RegistrationITKv4/ImageRegistration11.cxx, Examples/RegistrationITKv4/ImageRegistration14.cxx, Examples/RegistrationITKv4/ImageRegistration15.cxx, Examples/Segmentation/GeodesicActiveContourShapePriorLevelSetImageFilter.cxx, Examples/Statistics/BayesianPluginClassifier.cxx, Examples/Statistics/ExpectationMaximizationMixtureModelEstimator.cxx, Examples/Statistics/KdTreeBasedKMeansClustering.cxx, Examples/Statistics/NormalVariateGenerator.cxx, SphinxExamples/src/Numerics/Statistics/2DGaussianMixtureModelExpectMax/Code.cxx, and SphinxExamples/src/Numerics/Statistics/DistributeSamplingUsingGMM/Code.cxx.

Definition at line 98 of file itkNormalVariateGenerator.h.

Inheritance diagram for itk::Statistics::NormalVariateGenerator:

Collaboration diagram for itk::Statistics::NormalVariateGenerator:

Public Types
using	ConstPointer = SmartPointer< const Self >

using	Pointer = SmartPointer< Self >

using	Self = NormalVariateGenerator

using	Superclass = RandomVariateGeneratorBase

Public Types inherited from itk::Statistics::RandomVariateGeneratorBase
using	ConstPointer = SmartPointer< const Self >

using	Pointer = SmartPointer< Self >

using	Self = RandomVariateGeneratorBase

using	Superclass = Object

Public Types inherited from itk::Object
using	ConstPointer = SmartPointer< const Self >

using	Pointer = SmartPointer< Self >

using	Self = Object

using	Superclass = LightObject

Public Types inherited from itk::LightObject
using	ConstPointer = SmartPointer< const Self >

using	Pointer = SmartPointer< Self >

using	Self = LightObject

Public Member Functions
const char *	GetNameOfClass () const override

double	GetVariate () override

void	Initialize (int randomSeed)

Public Member Functions inherited from itk::Object
unsigned long	AddObserver (const EventObject &event, Command *)

unsigned long	AddObserver (const EventObject &event, Command *) const

unsigned long	AddObserver (const EventObject &event, std::function< void(const EventObject &)> function) const

LightObject::Pointer	CreateAnother () const override

virtual void	DebugOff () const

virtual void	DebugOn () const

Command *	GetCommand (unsigned long tag)

bool	GetDebug () const

MetaDataDictionary &	GetMetaDataDictionary ()

const MetaDataDictionary &	GetMetaDataDictionary () const

virtual ModifiedTimeType	GetMTime () const

virtual const TimeStamp &	GetTimeStamp () const

bool	HasObserver (const EventObject &event) const

void	InvokeEvent (const EventObject &)

void	InvokeEvent (const EventObject &) const

virtual void	Modified () const

void	Register () const override

void	RemoveAllObservers ()

void	RemoveObserver (unsigned long tag)

void	SetDebug (bool debugFlag) const

void	SetReferenceCount (int) override

void	UnRegister () const noexcept override

void	SetMetaDataDictionary (const MetaDataDictionary &rhs)

void	SetMetaDataDictionary (MetaDataDictionary &&rrhs)

virtual void	SetObjectName (std::string _arg)

virtual const std::string &	GetObjectName () const

Public Member Functions inherited from itk::LightObject
Pointer	Clone () const

virtual void	Delete ()

virtual int	GetReferenceCount () const

void	Print (std::ostream &os, Indent indent=0) const

Static Public Member Functions
static Pointer	New ()

Static Public Member Functions inherited from itk::Object
static bool	GetGlobalWarningDisplay ()

static void	GlobalWarningDisplayOff ()

static void	GlobalWarningDisplayOn ()

static Pointer	New ()

static void	SetGlobalWarningDisplay (bool val)

Static Public Member Functions inherited from itk::LightObject
static void	BreakOnError ()

static Pointer	New ()

Protected Member Functions
double	FastNorm ()

	NormalVariateGenerator ()

void	PrintSelf (std::ostream &os, Indent indent) const override

	~NormalVariateGenerator () override

Protected Member Functions inherited from itk::Statistics::RandomVariateGeneratorBase
	RandomVariateGeneratorBase ()

	~RandomVariateGeneratorBase () override

Protected Member Functions inherited from itk::Object
	Object ()

bool	PrintObservers (std::ostream &os, Indent indent) const

virtual void	SetTimeStamp (const TimeStamp &timeStamp)

	~Object () override

Protected Member Functions inherited from itk::LightObject
virtual LightObject::Pointer	InternalClone () const

	LightObject ()

virtual void	PrintHeader (std::ostream &os, Indent indent) const

virtual void	PrintTrailer (std::ostream &os, Indent indent) const

virtual	~LightObject ()

Static Private Member Functions
static int	SignedShiftXOR (int irs)

Private Attributes
double	m_ActualRSD {}

double	m_Chic1 {}

double	m_Chic2 {}

int	m_Gaussfaze {}

int *	m_Gausssave {}

double	m_GScale {}

int	m_Irs {}

int	m_Lseed {}

int	m_Nslew {}

double	m_Rcons {}

double	m_Rscale {}

double	m_Scale {}

int	m_Vec1 [m_TLEN] {}

Static Private Attributes
static constexpr int	m_ELEN { 7 }

static constexpr int	m_LEN { 128 }

static constexpr int	m_LMASK { 4 * (m_LEN - 1) }

static constexpr int	m_TLEN { 8 * m_LEN }

Additional Inherited Members
Protected Attributes inherited from itk::LightObject
std::atomic< int >	m_ReferenceCount {}

Member Typedef Documentation

◆ ConstPointer

using itk::Statistics::NormalVariateGenerator::ConstPointer = SmartPointer<const Self>

Definition at line 105 of file itkNormalVariateGenerator.h.

◆ Pointer

using itk::Statistics::NormalVariateGenerator::Pointer = SmartPointer<Self>

Definition at line 104 of file itkNormalVariateGenerator.h.

◆ Self

using itk::Statistics::NormalVariateGenerator::Self = NormalVariateGenerator

Standard class type aliases.

Definition at line 102 of file itkNormalVariateGenerator.h.

◆ Superclass

using itk::Statistics::NormalVariateGenerator::Superclass = RandomVariateGeneratorBase

Definition at line 103 of file itkNormalVariateGenerator.h.

Constructor & Destructor Documentation

◆ NormalVariateGenerator()

itk::Statistics::NormalVariateGenerator::NormalVariateGenerator ( )

protected

◆ ~NormalVariateGenerator()

itk::Statistics::NormalVariateGenerator::~NormalVariateGenerator ( )

overrideprotected

Member Function Documentation

◆ FastNorm()

double itk::Statistics::NormalVariateGenerator::FastNorm ( )

protected

get a variate

◆ GetNameOfClass()

const char* itk::Statistics::NormalVariateGenerator::GetNameOfClass ( ) const

overridevirtual

See also: LightObject::GetNameOfClass()

Reimplemented from itk::Statistics::RandomVariateGeneratorBase.

◆ GetVariate()

double itk::Statistics::NormalVariateGenerator::GetVariate ( )

overridevirtual

get a variate using FastNorm function

Implements itk::Statistics::RandomVariateGeneratorBase.

◆ Initialize()

void itk::Statistics::NormalVariateGenerator::Initialize ( int randomSeed )

generate random number table

◆ New()

static Pointer itk::Statistics::NormalVariateGenerator::New ( )

static

Method for creation through the object factory.

Examples: Examples/RegistrationITKv4/ModelToImageRegistration1.cxx.

◆ PrintSelf()

void itk::Statistics::NormalVariateGenerator::PrintSelf	(	std::ostream &	os,
		Indent	indent
	)		const

overrideprotectedvirtual

Methods invoked by Print() to print information about the object including superclasses. Typically not called by the user (use Print() instead) but used in the hierarchical print process to combine the output of several classes.

Reimplemented from itk::Object.