ITK  5.0.0
Insight Segmentation and Registration Toolkit
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itk::Statistics::NormalVariateGenerator Class Reference

#include <itkNormalVariateGenerator.h>

+ Inheritance diagram for itk::Statistics::NormalVariateGenerator:
+ Collaboration diagram for itk::Statistics::NormalVariateGenerator:

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 followings 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 maths 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 ARITHMATIC. 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/RegistrationITKv3/ImageRegistration11.cxx, Examples/RegistrationITKv3/ImageRegistration14.cxx, Examples/RegistrationITKv3/ImageRegistration15.cxx, 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, WikiExamples/Statistics/ExpectationMaximizationMixtureModelEstimator_2D.cxx, WikiExamples/Statistics/KdTreeBasedKMeansClustering1D.cxx, and WikiExamples/Statistics/KdTreeBasedKMeansClustering3D.cxx.

Definition at line 98 of file itkNormalVariateGenerator.h.

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

virtual ::itk::LightObject::Pointer CreateAnother () const
 
virtual const char * GetNameOfClass () const
 
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
 
virtual void DebugOff () const
 
virtual void DebugOn () const
 
CommandGetCommand (unsigned long tag)
 
bool GetDebug () const
 
MetaDataDictionaryGetMetaDataDictionary ()
 
const MetaDataDictionaryGetMetaDataDictionary () const
 
virtual ModifiedTimeType GetMTime () const
 
virtual const TimeStampGetTimeStamp () 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 noexceptoverride
 
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
virtual void Delete ()
 
virtual int GetReferenceCount () const
 
 itkCloneMacro (Self)
 
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 flag)
 
- 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 &time)
 
 ~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_ELEN
 
int m_Gaussfaze
 
int * m_Gausssave
 
double m_GScale
 
int m_Irs
 
int m_LEN
 
int m_LMASK
 
int m_Lseed
 
int m_Nslew
 
double m_Rcons
 
double m_Rscale
 
double m_Scale
 
int m_TLEN
 
int * m_Vec1
 

Additional Inherited Members

- Protected Attributes inherited from itk::LightObject
std::atomic< int > m_ReferenceCount
 

Member Typedef Documentation

Definition at line 106 of file itkNormalVariateGenerator.h.

Definition at line 105 of file itkNormalVariateGenerator.h.

Standard class type aliases.

Definition at line 103 of file itkNormalVariateGenerator.h.

Definition at line 104 of file itkNormalVariateGenerator.h.

Constructor & Destructor Documentation

itk::Statistics::NormalVariateGenerator::NormalVariateGenerator ( )
protected
itk::Statistics::NormalVariateGenerator::~NormalVariateGenerator ( )
overrideprotected

Member Function Documentation

virtual::itk::LightObject::Pointer itk::Statistics::NormalVariateGenerator::CreateAnother ( ) const
virtual

Create an object from an instance, potentially deferring to a factory. This method allows you to create an instance of an object that is exactly the same type as the referring object. This is useful in cases where an object has been cast back to a base class.

Reimplemented from itk::Object.

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

get a variate

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

Run-time type information (and related methods).

Reimplemented from itk::Statistics::RandomVariateGeneratorBase.

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

get a variate using FastNorm function

Implements itk::Statistics::RandomVariateGeneratorBase.

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

generate random number table

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

static int itk::Statistics::NormalVariateGenerator::SignedShiftXOR ( int  irs)
inlinestaticprivate

Definition at line 131 of file itkNormalVariateGenerator.h.

Member Data Documentation

double itk::Statistics::NormalVariateGenerator::m_ActualRSD
private

Definition at line 159 of file itkNormalVariateGenerator.h.

double itk::Statistics::NormalVariateGenerator::m_Chic1
private

Definition at line 157 of file itkNormalVariateGenerator.h.

double itk::Statistics::NormalVariateGenerator::m_Chic2
private

Definition at line 158 of file itkNormalVariateGenerator.h.

int itk::Statistics::NormalVariateGenerator::m_ELEN
private

Definition at line 143 of file itkNormalVariateGenerator.h.

int itk::Statistics::NormalVariateGenerator::m_Gaussfaze
private

Definition at line 148 of file itkNormalVariateGenerator.h.

int* itk::Statistics::NormalVariateGenerator::m_Gausssave
private

Definition at line 149 of file itkNormalVariateGenerator.h.

double itk::Statistics::NormalVariateGenerator::m_GScale
private

Definition at line 151 of file itkNormalVariateGenerator.h.

int itk::Statistics::NormalVariateGenerator::m_Irs
private

Definition at line 155 of file itkNormalVariateGenerator.h.

int itk::Statistics::NormalVariateGenerator::m_LEN
private

Definition at line 144 of file itkNormalVariateGenerator.h.

int itk::Statistics::NormalVariateGenerator::m_LMASK
private

Definition at line 145 of file itkNormalVariateGenerator.h.

int itk::Statistics::NormalVariateGenerator::m_Lseed
private

Definition at line 156 of file itkNormalVariateGenerator.h.

int itk::Statistics::NormalVariateGenerator::m_Nslew
private

Definition at line 154 of file itkNormalVariateGenerator.h.

double itk::Statistics::NormalVariateGenerator::m_Rcons
private

Definition at line 142 of file itkNormalVariateGenerator.h.

double itk::Statistics::NormalVariateGenerator::m_Rscale
private

Definition at line 141 of file itkNormalVariateGenerator.h.

double itk::Statistics::NormalVariateGenerator::m_Scale
private

Definition at line 140 of file itkNormalVariateGenerator.h.

int itk::Statistics::NormalVariateGenerator::m_TLEN
private

Definition at line 146 of file itkNormalVariateGenerator.h.

int* itk::Statistics::NormalVariateGenerator::m_Vec1
private

Definition at line 153 of file itkNormalVariateGenerator.h.


The documentation for this class was generated from the following file: