inf.util
Class BiasedRandom

java.lang.Object
  inf.util.BiasedRandom

public abstract class BiasedRandom
extends java.lang.Object

This class represents a source of randomness that, unlike java.util.Random, returns random numbers according to a non-uniform distribution. The random number generators provided by this class all use Random.nextDouble() as the underlying source of randomness. Only EXP10_0 incurs a significant performance overhead compared to the source.

Author:

Gerhard Wickler

Field Summary

static BiasedRandom	EXP10_0 A zero-biased source of random numbers.
static BiasedRandom	LINEAR_0 A zero-biased source of random numbers.
static BiasedRandom	POLY2_0 A zero-biased source of random numbers.
static BiasedRandom	POLY4_0 A zero-biased source of random numbers.
static BiasedRandom	POLY8_0 A zero-biased source of random numbers.

Constructor Summary

BiasedRandom()

Method Summary

abstract double	nextDouble() This function returns a biased random double from the range 0.0d (inclusive) to 1.0d (exclusive).
int	nextInt(int n) This function returns a biased random double int 0 and n-1 (both inclusive).

Methods inherited from class java.lang.Object

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

Field Detail

LINEAR_0

public static final BiasedRandom LINEAR_0

A zero-biased source of random numbers. The numbers are biased towards 0 according a linear distribution.

POLY2_0

public static final BiasedRandom POLY2_0

A zero-biased source of random numbers. The numbers are biased towards 0 according a polynomial (degree 2) distribution.

POLY4_0

public static final BiasedRandom POLY4_0

A zero-biased source of random numbers. The numbers are biased towards 0 according a polynomial (degree 4) distribution.

POLY8_0

public static final BiasedRandom POLY8_0

A zero-biased source of random numbers. The numbers are biased towards 0 according a polynomial (degree 8) distribution.

EXP10_0

public static final BiasedRandom EXP10_0

A zero-biased source of random numbers. The numbers are biased towards 0 according a exponential distribution. Note: This random number generator is significantly slower than the polynomial ones and tends to be less biased than for example POLY8_0.

Constructor Detail

BiasedRandom

public BiasedRandom()

Method Detail

nextDouble

public abstract double nextDouble()

This function returns a biased random double from the range 0.0d (inclusive) to 1.0d (exclusive).

Returns:

a biased random double

nextInt

public int nextInt(int n)

This function returns a biased random double int 0 and n-1 (both inclusive).

Returns:

a biased random int