nl.tudelft.simulation.jstats.streams
Class RandomNumberGenerator

java.lang.Object
  nl.tudelft.simulation.jstats.streams.RandomNumberGenerator

All Implemented Interfaces:

java.io.Serializable, StreamInterface

Direct Known Subclasses:

DX120Generator, MersenneTwister

public abstract class RandomNumberGenerator

extends java.lang.Object

implements StreamInterface

The RandomNumberGenerator class provides an abstract for all pseudo random number generators.

(c) copyright 2004 Delft University of Technology , the Netherlands.
See for project information www.simulation.tudelft.nl
License of use: General Public License (GPL) , no warranty

Since:

1.0

Version:

1.6 2004-03-18

Author:

Peter Jacobs

See Also:

Serialized Form

Field Summary

protected long

seed the seed of the generator

Constructor Summary

RandomNumberGenerator()
constructs a new RandomNumberGenerator.

RandomNumberGenerator(long seed)
constructs a new RandomNumberGenerator.

Method Summary

long	getSeed() returns the seed of the generator
protected abstract long	next(int bits) returns the next value in the stream.
boolean	nextBoolean() Returns the next pseudorandom, uniformly distributed boolean value from this random number generator's sequence.
double	nextDouble() Returns the next pseudorandom, uniformly distributed double value between 0.0 and 1.0 from this random number generator's sequence.
float	nextFloat() Returns the next pseudorandom, uniformly distributed float value between 0.0 and 1.0 from this random number generator's sequence.
int	nextInt() Returns the next pseudorandom, uniformly distributed int value from this random number generator's sequence.
int	nextInt(int i, int j) Returns a pseudorandom, uniformly distributed int value between i (inclusive) and j, drawn from this random number generator's sequence.
long	nextLong() Returns the next pseudorandom, uniformly distributed long value from this random number generator's sequence.
void	reset() resets the stream
abstract void	setSeed(long seed) sets the seed of the generator
java.lang.String	toString()

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Field Detail

seed

protected long seed

the seed of the generator

Constructor Detail

RandomNumberGenerator

public RandomNumberGenerator()

constructs a new RandomNumberGenerator. The seed value used in the rng is set to System.currentTimeMillis();

RandomNumberGenerator

public RandomNumberGenerator(long seed)

constructs a new RandomNumberGenerator.

Parameters:

seed - the seed of the generator.

Method Detail

reset

public void reset()

Description copied from interface: StreamInterface

resets the stream

Specified by:

reset in interface StreamInterface

See Also:

StreamInterface.reset()

next

protected abstract long next(int bits)

returns the next value in the stream.

Parameters:

bits - the number of bits used

Returns:

the next value.

nextBoolean

public boolean nextBoolean()

Returns the next pseudorandom, uniformly distributed boolean value from this random number generator's sequence. The general contract of nextBoolean is that one boolean value is pseudorandomly generated and returned. The values true and false are produced with (approximately) equal probability. The method nextBoolean is implemented by class Random as follows:

 public boolean nextBoolean()
 {
 	return next(1) != 0;
 }
 

Specified by:

nextBoolean in interface StreamInterface

Returns:

the next pseudorandom, uniformly distributed boolean value from this random number generator's sequence.

Since:

1.2

nextDouble

public double nextDouble()

Returns the next pseudorandom, uniformly distributed double value between 0.0 and 1.0 from this random number generator's sequence.

The general contract of nextDouble is that one double value, chosen (approximately) uniformly from the range 0.0d (inclusive) to 1.0d (exclusive), is pseudorandomly generated and returned. All 2 ⁶⁴ possible float values of the form m x 2 ^-64 , where m is a positive integer less than 2 ⁶⁴ , are produced with (approximately) equal probability.

Specified by:

nextDouble in interface StreamInterface

Returns:

the next pseudorandom, uniformly distributed double value between 0.0 and 1.0 from this random number generator's sequence.

nextFloat

public float nextFloat()

Returns the next pseudorandom, uniformly distributed float value between 0.0 and 1.0 from this random number generator's sequence.

The general contract of nextFloat is that one float value, chosen (approximately) uniformly from the range 0.0f (inclusive) to 1.0f (exclusive), is pseudorandomly generated and returned. All 2 ²⁴ possible float values of the form m x 2 ^-24 , where m is a positive integer less than 2 ²⁴ , are produced with (approximately) equal probability. The method nextFloat is implemented by class Random as follows:

 
  
    public float nextFloat() {
    return next(24) / ((float)(1 < < 24));
    }
  
 

The hedge "approximately" is used in the foregoing description only because the next method is only approximately an unbiased source of independently chosen bits. If it were a perfect source or randomly chosen bits, then the algorithm shown would choose float values from the stated range with perfect uniformity.

Specified by:

nextFloat in interface StreamInterface

Returns:

the next pseudorandom, uniformly distributed float value between 0.0 and 1.0 from this random number generator's sequence.

nextInt

public int nextInt()

Returns the next pseudorandom, uniformly distributed int value from this random number generator's sequence. The general contract of nextInt is that one int value is pseudorandomly generated and returned. All 2 ³² possible int values are produced with (approximately) equal probability. The method nextInt is implemented by class Random as follows:

 public int nextInt()
 {
 	return next(32);
 }
 

Specified by:

nextInt in interface StreamInterface

Returns:

the next pseudorandom, uniformly distributed int value from this random number generator's sequence.

nextInt

public int nextInt(int i,
                   int j)

Returns a pseudorandom, uniformly distributed int value between i (inclusive) and j, drawn from this random number generator's sequence. The general contract of nextInt is that one int value in the specified range is pseudorandomly generated and returned. All n possible int values are produced with (approximately) equal probability.

Specified by:

nextInt in interface StreamInterface

Parameters:

i - the lower value

j - the higher value

Returns:

the result

nextLong

public long nextLong()

Returns the next pseudorandom, uniformly distributed long value from this random number generator's sequence. The general contract of nextLong is that one long value is pseudorandomly generated and returned. All 2 ⁶⁴ possible long values are produced with (approximately) equal probability. The method nextLong is implemented by class Random as follows:

 
  
    public long nextLong() {
    return ((long)next(32) < < 32) + next(32);
    }
  
 

Specified by:

nextLong in interface StreamInterface

Returns:

the next pseudorandom, uniformly distributed long value from this random number generator's sequence.

setSeed

public abstract void setSeed(long seed)

Description copied from interface: StreamInterface

sets the seed of the generator

Specified by:

setSeed in interface StreamInterface

Parameters:

seed - the new seed

See Also:

StreamInterface.setSeed(long)

getSeed

public long getSeed()

Description copied from interface: StreamInterface

returns the seed of the generator

Specified by:

getSeed in interface StreamInterface

Returns:

long the seed

See Also:

StreamInterface.getSeed()

toString

public java.lang.String toString()

See Also:

Object.toString()