umontreal.iro.lecuyer.rng
Class TruncatedRandomStream

java.lang.Object
  umontreal.iro.lecuyer.rng.TruncatedRandomStream

All Implemented Interfaces:

RandomStream

public class TruncatedRandomStream
extends Object
implements RandomStream

Represents a container random stream generating numbers in an interval (a, b) instead of in (0, 1), where 0 <= a < b <= 1, by using the contained stream. If nextDouble returns u for the contained stream, it will return v = a + (b - a)u, which is uniform over (a, b), for the truncated stream. The method nextInt returns the integer that corresponds to v (by inversion); this integer is no longer uniformly distributed in general.

Constructor Summary

TruncatedRandomStream(RandomStream stream, double a, double b)

Method Summary

void	nextArrayOfDouble(double[] u, int start, int n) Generates n (pseudo)random numbers from the uniform distribution and stores them into the array u starting at index start.
void	nextArrayOfInt(int i, int j, int[] u, int start, int n) Generates n (pseudo)random numbers from the discrete uniform distribution over the integers {i, i + 1,..., j}, using this stream and stores the result in the array u starting at index start.
double	nextDouble() Returns a (pseudo)random number from the uniform distribution over the interval (0, 1), using this stream, after advancing its state by one step.
int	nextInt(int i, int j) Returns a (pseudo)random number from the discrete uniform distribution over the integers {i, i + 1,..., j}, using this stream.
void	resetNextSubstream() Reinitializes the stream to the beginning of its next substream: Ng is computed, and Cg and Bg are set to Ng.
void	resetStartStream() Reinitializes the stream to its initial state Ig: Cg and Bg are set to Ig.
void	resetStartSubstream() Reinitializes the stream to the beginning of its current substream: Cg is set to Bg.

Methods inherited from class java.lang.Object

equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Methods inherited from interface umontreal.iro.lecuyer.rng.RandomStream

toString

Constructor Detail

TruncatedRandomStream

public TruncatedRandomStream(RandomStream stream,
                             double a,
                             double b)

Method Detail

resetStartStream

public void resetStartStream()

Description copied from interface: RandomStream

Reinitializes the stream to its initial state I_g: C_g and B_g are set to I_g.

Specified by:

resetStartStream in interface RandomStream

resetStartSubstream

public void resetStartSubstream()

Description copied from interface: RandomStream

Reinitializes the stream to the beginning of its current substream: C_g is set to B_g.

Specified by:

resetStartSubstream in interface RandomStream

resetNextSubstream

public void resetNextSubstream()

Description copied from interface: RandomStream

Reinitializes the stream to the beginning of its next substream: N_g is computed, and C_g and B_g are set to N_g.

Specified by:

resetNextSubstream in interface RandomStream

nextDouble

public double nextDouble()

Description copied from interface: RandomStream

Returns a (pseudo)random number from the uniform distribution over the interval (0, 1), using this stream, after advancing its state by one step. The generators programmed in SSJ never return the values 0 or 1.

Specified by:

nextDouble in interface RandomStream

Returns:

the next generated uniform

nextArrayOfDouble

public void nextArrayOfDouble(double[] u,
                              int start,
                              int n)

Description copied from interface: RandomStream

Generates n (pseudo)random numbers from the uniform distribution and stores them into the array u starting at index start.

Specified by:

nextArrayOfDouble in interface RandomStream

Parameters:

u - array that will contain the generated uniforms

start - starting index, in the array u, to write uniforms from

n - number of uniforms to generate

nextInt

public int nextInt(int i,
                   int j)

Description copied from interface: RandomStream

Returns a (pseudo)random number from the discrete uniform distribution over the integers {i, i + 1,..., j}, using this stream. (Calls nextDouble once.)

Specified by:

nextInt in interface RandomStream

Parameters:

i - smallest integer that can be generated

j - greatest integer that can be generated

Returns:

the generated integer

nextArrayOfInt

public void nextArrayOfInt(int i,
                           int j,
                           int[] u,
                           int start,
                           int n)

Description copied from interface: RandomStream

Generates n (pseudo)random numbers from the discrete uniform distribution over the integers {i, i + 1,..., j}, using this stream and stores the result in the array u starting at index start. (Calls nextInt n times.)

Specified by:

nextArrayOfInt in interface RandomStream

Parameters:

i - smallest integer that can be generated

j - greatest integer that can be generated

u - array that will contain the generated values

start - starting index, in the array u, to write integers from

n - number of values being generated