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itk::Statistics::NormalVariateGenerator Class Reference

#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)

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)
 
const char * GetNameOfClass () const override
 
virtual double GetVariate ()=0
 
- Public Member Functions inherited from itk::Object
unsigned long AddObserver (const EventObject &event, Command *cmd) 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
 
CommandGetCommand (unsigned long tag)
 
bool GetDebug () const
 
MetaDataDictionaryGetMetaDataDictionary ()
 
const MetaDataDictionaryGetMetaDataDictionary () const
 
virtual ModifiedTimeType GetMTime () const
 
const char * GetNameOfClass () const override
 
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) const
 
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 Pointer CreateAnother () const
 
virtual void Delete ()
 
virtual const char * GetNameOfClass () const
 
virtual int GetReferenceCount () const
 
void Print (std::ostream &os, Indent indent=0) const
 
virtual void Register () const
 
virtual void SetReferenceCount (int)
 
virtual void UnRegister () const noexcept
 

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

Definition at line 105 of file itkNormalVariateGenerator.h.

◆ Pointer

Definition at line 104 of file itkNormalVariateGenerator.h.

◆ Self

Standard class type aliases.

Definition at line 102 of file itkNormalVariateGenerator.h.

◆ Superclass

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

◆ 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.

◆ 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.

◆ SignedShiftXOR()

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

Definition at line 133 of file itkNormalVariateGenerator.h.

Member Data Documentation

◆ m_ActualRSD

double itk::Statistics::NormalVariateGenerator::m_ActualRSD {}
private

Definition at line 163 of file itkNormalVariateGenerator.h.

◆ m_Chic1

double itk::Statistics::NormalVariateGenerator::m_Chic1 {}
private

Definition at line 161 of file itkNormalVariateGenerator.h.

◆ m_Chic2

double itk::Statistics::NormalVariateGenerator::m_Chic2 {}
private

Definition at line 162 of file itkNormalVariateGenerator.h.

◆ m_ELEN

constexpr int itk::Statistics::NormalVariateGenerator::m_ELEN { 7 }
staticconstexprprivate

Definition at line 146 of file itkNormalVariateGenerator.h.

◆ m_Gaussfaze

int itk::Statistics::NormalVariateGenerator::m_Gaussfaze {}
private

Definition at line 152 of file itkNormalVariateGenerator.h.

◆ m_Gausssave

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

Definition at line 153 of file itkNormalVariateGenerator.h.

◆ m_GScale

double itk::Statistics::NormalVariateGenerator::m_GScale {}
private

Definition at line 155 of file itkNormalVariateGenerator.h.

◆ m_Irs

int itk::Statistics::NormalVariateGenerator::m_Irs {}
private

Definition at line 159 of file itkNormalVariateGenerator.h.

◆ m_LEN

constexpr int itk::Statistics::NormalVariateGenerator::m_LEN { 128 }
staticconstexprprivate

Definition at line 148 of file itkNormalVariateGenerator.h.

◆ m_LMASK

constexpr int itk::Statistics::NormalVariateGenerator::m_LMASK { 4 * (m_LEN - 1) }
staticconstexprprivate

Definition at line 149 of file itkNormalVariateGenerator.h.

◆ m_Lseed

int itk::Statistics::NormalVariateGenerator::m_Lseed {}
private

Definition at line 160 of file itkNormalVariateGenerator.h.

◆ m_Nslew

int itk::Statistics::NormalVariateGenerator::m_Nslew {}
private

Definition at line 158 of file itkNormalVariateGenerator.h.

◆ m_Rcons

double itk::Statistics::NormalVariateGenerator::m_Rcons {}
private

Definition at line 144 of file itkNormalVariateGenerator.h.

◆ m_Rscale

double itk::Statistics::NormalVariateGenerator::m_Rscale {}
private

Definition at line 143 of file itkNormalVariateGenerator.h.

◆ m_Scale

double itk::Statistics::NormalVariateGenerator::m_Scale {}
private

Definition at line 142 of file itkNormalVariateGenerator.h.

◆ m_TLEN

constexpr int itk::Statistics::NormalVariateGenerator::m_TLEN { 8 * m_LEN }
staticconstexprprivate

Definition at line 150 of file itkNormalVariateGenerator.h.

◆ m_Vec1

int itk::Statistics::NormalVariateGenerator::m_Vec1[m_TLEN] {}
private

Definition at line 157 of file itkNormalVariateGenerator.h.


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