ITK  4.3.0
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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)

Definition at line 97 of file itkNormalVariateGenerator.h.

Public Types

typedef SmartPointer< const SelfConstPointer
 
typedef SmartPointer< SelfPointer
 
typedef NormalVariateGenerator Self
 
typedef RandomVariateGeneratorBase Superclass
 
- Public Types inherited from itk::Statistics::RandomVariateGeneratorBase
typedef SmartPointer< const SelfConstPointer
 
typedef SmartPointer< SelfPointer
 
typedef RandomVariateGeneratorBase Self
 
typedef Object Superclass
 
- Public Types inherited from itk::Object
typedef SmartPointer< const SelfConstPointer
 
typedef SmartPointer< SelfPointer
 
typedef Object Self
 
typedef LightObject Superclass
 
- Public Types inherited from itk::LightObject
typedef SmartPointer< const SelfConstPointer
 
typedef SmartPointer< SelfPointer
 
typedef LightObject Self
 

Public Member Functions

virtual ::itk::LightObject::Pointer CreateAnother (void) const
 
virtual const char * GetNameOfClass () const
 
double GetVariate ()
 
void Initialize (int randomSeed)
 

Static Public Member Functions

static Pointer New ()
 

Protected Member Functions

double FastNorm (void)
 
 NormalVariateGenerator ()
 
virtual void PrintSelf (std::ostream &os, Indent indent) const
 
virtual ~NormalVariateGenerator ()
 
- Protected Member Functions inherited from itk::Statistics::RandomVariateGeneratorBase
 RandomVariateGeneratorBase ()
 
virtual ~RandomVariateGeneratorBase ()
 
- Protected Member Functions inherited from itk::Object
 Object ()
 
bool PrintObservers (std::ostream &os, Indent indent) const
 
virtual void SetTimeStamp (const TimeStamp &time)
 
virtual ~Object ()
 
- 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 ()
 

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 Types inherited from itk::LightObject
typedef int InternalReferenceCountType
 
- Protected Attributes inherited from itk::LightObject
InternalReferenceCountType m_ReferenceCount
 
SimpleFastMutexLock m_ReferenceCountLock
 

Member Typedef Documentation

Definition at line 105 of file itkNormalVariateGenerator.h.

Definition at line 104 of file itkNormalVariateGenerator.h.

Standard class typedefs.

Definition at line 102 of file itkNormalVariateGenerator.h.

Definition at line 103 of file itkNormalVariateGenerator.h.

Constructor & Destructor Documentation

itk::Statistics::NormalVariateGenerator::NormalVariateGenerator ( )
protected
virtual itk::Statistics::NormalVariateGenerator::~NormalVariateGenerator ( )
protectedvirtual

Member Function Documentation

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

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

Method for creation through the object factory.

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

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.

Member Data Documentation

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

Definition at line 148 of file itkNormalVariateGenerator.h.

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

Definition at line 146 of file itkNormalVariateGenerator.h.

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

Definition at line 147 of file itkNormalVariateGenerator.h.

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

Definition at line 132 of file itkNormalVariateGenerator.h.

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

Definition at line 137 of file itkNormalVariateGenerator.h.

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

Definition at line 138 of file itkNormalVariateGenerator.h.

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

Definition at line 140 of file itkNormalVariateGenerator.h.

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

Definition at line 144 of file itkNormalVariateGenerator.h.

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

Definition at line 133 of file itkNormalVariateGenerator.h.

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

Definition at line 134 of file itkNormalVariateGenerator.h.

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

Definition at line 145 of file itkNormalVariateGenerator.h.

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

Definition at line 143 of file itkNormalVariateGenerator.h.

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

Definition at line 131 of file itkNormalVariateGenerator.h.

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

Definition at line 130 of file itkNormalVariateGenerator.h.

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

Definition at line 129 of file itkNormalVariateGenerator.h.

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

Definition at line 135 of file itkNormalVariateGenerator.h.

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

Definition at line 142 of file itkNormalVariateGenerator.h.


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