This class provides a convenient foundation on which RNGs can be built. More...

Inheritance diagram for umontreal.ssj.rng.RandomStreamBase:

Public Member Functions
abstract void	resetStartStream ()
	Reinitializes the stream to its initial state \(I_g\): \(C_g\) and \(B_g\) are set to \(I_g\).
abstract void	resetStartSubstream ()
	Reinitializes the stream to the beginning of its current substream:
abstract void	resetNextSubstream ()
	Reinitializes the stream to the beginning of its next substream:
abstract String	toString ()
	Returns a string containing the current state of this stream.
void	increasedPrecision (boolean incp)
	After calling this method with incp = true, each call to the RNG (direct or indirect) for this stream will return a uniform random number with more bits of precision than what is returned by nextValue, and will advance the state of the stream by 2 steps instead of 1 (i.e., nextValue will be called twice for each random number).
double	nextDouble ()
	Returns a uniform random number between 0 and 1 from the stream.
void	nextArrayOfDouble (double[] u, int start, int n)
	Calls nextDouble n times to fill the array u.
int	nextInt (int i, int j)
	Calls nextDouble once to create one integer between i and j.
void	nextArrayOfInt (int i, int j, int[] u, int start, int n)
	Calls nextInt n times to fill the array u.
String	formatState ()
	Use the toString method.
String	formatStateFull ()
	Use the toStringFull method.
RandomStreamBase	clone ()
	Clones the current generator and return its copy.

Protected Member Functions
abstract double	nextValue ()
	This method should return the next random number (between 0 and 1) from the current stream.

Detailed Description

This class provides a convenient foundation on which RNGs can be built.

It implements all the methods which do not depend directly on the generator itself, but only on its output, which is to be defined by implementing the abstract method nextValue. In the present class, all methods returning random numbers directly or indirectly (nextDouble, nextArrayOfDouble, nextInt and nextArrayOfInt) call nextValue. Thus, to define a subclass that implements a RNG, it suffices to implement nextValue, in addition to the reset... and toString methods. Of course, the other methods may also be overridden for improved efficiency.

If the nextValue already generates numbers with a precision of 53-bits or higher, then nextDouble can be overridden to improve the performance. The mechanism for increasing the precision assumes that nextValue returns at least 29 bits of precision, in which case the higher precision numbers will have roughly 52 bits of precision. This mechanism was designed primarily for RNGs that return numbers with around 30 to 32 bits of precision.

RandomStreamBase and its subclasses are implementing the Serializable interface. Each class has a serial number wich represent the class version. For instance 70510 means that the last change was the 10th May 2007.

Definition at line 54 of file RandomStreamBase.java.

Member Function Documentation

◆ clone()

RandomStreamBase umontreal.ssj.rng.RandomStreamBase.clone ( )

Clones the current generator and return its copy.

Returns: A deep copy of the current generator

Implements umontreal.ssj.rng.CloneableRandomStream.

Reimplemented in umontreal.ssj.mcqmctools.anova.SplitStream, umontreal.ssj.rng.LFSR113, umontreal.ssj.rng.LFSR258, umontreal.ssj.rng.MRG31k3p, umontreal.ssj.rng.MRG32k3a, umontreal.ssj.rng.MRG32k3aL, and umontreal.ssj.rng.WELL512.

Definition at line 210 of file RandomStreamBase.java.

◆ formatState()

String umontreal.ssj.rng.RandomStreamBase.formatState ( )

Use the toString method.

Definition at line 193 of file RandomStreamBase.java.

◆ formatStateFull()

String umontreal.ssj.rng.RandomStreamBase.formatStateFull ( )

Use the toStringFull method.

Definition at line 201 of file RandomStreamBase.java.

◆ increasedPrecision()

void umontreal.ssj.rng.RandomStreamBase.increasedPrecision ( boolean incp )

After calling this method with incp = true, each call to the RNG (direct or indirect) for this stream will return a uniform random number with more bits of precision than what is returned by nextValue, and will advance the state of the stream by 2 steps instead of 1 (i.e., nextValue will be called twice for each random number).

More precisely, if s is a stream of a subclass of RandomStreamBase, when the precision has been increased, the instruction "<tt>u = s.nextDouble()</tt>", is equivalent to "<tt>u = (s.nextValue() + s.nextValue()*fact) % 1.0</tt>" where the constant fact is equal to \(2^{-24}\). This also applies when calling nextDouble indirectly (e.g., via nextInt, etc.). By default, or if this method is called again with incp = false, each call to nextDouble for this stream advances the state by 1 step and returns the same number as nextValue.

Parameters

incp	if the generator will be set to high precision mode

Definition at line 95 of file RandomStreamBase.java.

◆ nextArrayOfDouble()

void umontreal.ssj.rng.RandomStreamBase.nextArrayOfDouble	(	double[]	u,
		int	start,
		int	n )

Calls nextDouble n times to fill the array u.

Parameters

u	the array in which the numbers will be stored
start	the first index of u to be used
n	the number of random numbers to put in u

Implements umontreal.ssj.rng.RandomStream.

Definition at line 134 of file RandomStreamBase.java.

◆ nextArrayOfInt()

void umontreal.ssj.rng.RandomStreamBase.nextArrayOfInt	(	int	i,
		int	j,
		int[]	u,
		int	start,
		int	n )

Calls nextInt n times to fill the array u.

This method should be overridden if a faster implementation exists for the specific generator.

Parameters

i	the smallest possible integer to put in u
j	the largest possible integer to put in u
u	the array in which the numbers will be stored
start	the first index of u to be used
n	the number of random numbers to put in u

Implements umontreal.ssj.rng.RandomStream.

Definition at line 175 of file RandomStreamBase.java.

◆ nextDouble()

double umontreal.ssj.rng.RandomStreamBase.nextDouble ( )

Returns a uniform random number between 0 and 1 from the stream.

Its behavior depends on the last call to increasedPrecision. The generators programmed in SSJ never return the values 0 or 1.

Returns: a number in the interval (0,1)

Implements umontreal.ssj.rng.RandomStream.

Definition at line 117 of file RandomStreamBase.java.

◆ nextInt()

int umontreal.ssj.rng.RandomStreamBase.nextInt	(	int	i,
		int	j )

Calls nextDouble once to create one integer between i and j.

This method always uses the highest order bits of the random number. It should be overridden if a faster implementation exists for the specific generator.

Parameters

i	the smallest possible returned integer
j	the largest possible returned integer

Returns: a random integer between i and j

Implements umontreal.ssj.rng.RandomStream.

Reimplemented in umontreal.ssj.rng.LFSR113, and umontreal.ssj.rng.LFSR258.

Definition at line 157 of file RandomStreamBase.java.

◆ nextValue()

abstract double umontreal.ssj.rng.RandomStreamBase.nextValue ( )

abstractprotected

This method should return the next random number (between 0 and 1) from the current stream.

If the stream is set to the high precision mode (increasedPrecision(true) was called), then each call to nextDouble will call nextValue twice, otherwise it will call it only once.