umontreal.iro.lecuyer.rng
Class AntitheticStream

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

All Implemented Interfaces:

RandomStream

public class AntitheticStream
extends Object
implements RandomStream

This container class allows the user to force any RandomStream to return antithetic variates. That is, nextDouble returns 1 - u instead of u and the corresponding change is made in nextInt. Any instance of this class behaves exactly like a RandomStream, except that it depends on another random number generator stream, called the base stream, to generate its numbers. Any call to one of the next... methods of this class will modify the state of the base stream.

Constructor Summary

AntitheticStream(RandomStream stream)
Constructs a new antithetic stream, using the random numbers from the base stream stream.

Method Summary

void	nextArrayOfDouble(double[] u, int start, int n) Calls nextArrayOfDouble (u, start, n) for the base stream, then replaces each u[i] by 1.0 - u[i].
void	nextArrayOfInt(int i, int j, int[] u, int start, int n) Calls nextArrayOfInt (i, j, u, start, n) for the base stream, then replaces each u[i] by j - i - u[i].
double	nextDouble() Returns 1.0 - s.nextDouble() where s is the base stream.
int	nextInt(int i, int j) Returns j - i - s.nextInt(i, j) where s is the base 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.
String	toString() Returns a string starting with "Antithetic of " and finishing with the result of the call to the toString method of the generator.

Methods inherited from class java.lang.Object

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

Constructor Detail

AntitheticStream

public AntitheticStream(RandomStream stream)

Constructs a new antithetic stream, using the random numbers from the base stream stream.

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

toString

public String toString()

Returns a string starting with "Antithetic of " and finishing with the result of the call to the toString method of the generator.

Specified by:

toString in interface RandomStream

Overrides:

toString in class Object

Returns:

the state of the generator formated as a string

nextDouble

public double nextDouble()

Returns 1.0 - s.nextDouble() where s is the base stream.

Specified by:

nextDouble in interface RandomStream

Returns:

the next generated uniform

nextInt

public int nextInt(int i,
                   int j)

Returns j - i - s.nextInt(i, j) where s is the base stream.

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

nextArrayOfDouble

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

Calls nextArrayOfDouble (u, start, n) for the base stream, then replaces each u[i] by 1.0 - u[i].

Specified by:

nextArrayOfDouble in interface RandomStream

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

nextArrayOfInt

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

Calls nextArrayOfInt (i, j, u, start, n) for the base stream, then replaces each u[i] by j - i - u[i].

Specified by:

nextArrayOfInt in interface RandomStream

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