cern.jet.random.engine
Class RandomEngine

java.lang.Object
  cern.colt.PersistentObject
      edu.cornell.lassp.houle.RngPack.RandomElement
          edu.cornell.lassp.houle.RngPack.RandomSeedable
              cern.jet.random.engine.RandomEngine

All Implemented Interfaces:

DoubleFunction, IntFunction, java.io.Serializable, java.lang.Cloneable

Direct Known Subclasses:

MersenneTwister

public abstract class RandomEngine
extends RandomSeedable
implements DoubleFunction, IntFunction

Abstract base class for uniform pseudo-random number generating engines.

Most probability distributions are obtained by using a uniform pseudo-random number generation engine (derived from this class or RandomElement) followed by a transformation to the desired distribution. Thus, subclasses of this class are at the core of computational statistics, simulations, Monte Carlo methods, etc.

Subclasses produce uniformly distributed int's and long's in the closed intervals [Integer.MIN_VALUE,Integer.MAX_VALUE] and [Long.MIN_VALUE,Long.MAX_VALUE], respectively, as well as float's and double's in the open unit intervals (0.0f,1.0f) and (0.0,1.0), respectively.

Subclasses need to override one single method only: nextInt(). All other methods generating different data types or ranges are usually layered upon nextInt(). long's are formed by concatenating two 32 bit int's. float's are formed by dividing the interval [0.0f,1.0f] into 2³² sub intervals, then randomly choosing one subinterval. double's are formed by dividing the interval [0.0,1.0] into 2⁶⁴ sub intervals, then randomly choosing one subinterval.

Note that this implementation is not synchronized.

Version:

1.0, 09/24/99

Author:

wolfgang.hoschek@cern.ch

See Also:

MersenneTwister, Ranmar, Ranlux, Ranecu, Random, Serialized Form

Method Summary

double	apply(double dummy) Equivalent to raw().
int	apply(int dummy) Equivalent to nextInt().
static RandomElement	makeDefault() Constructs and returns a new uniform random number engine seeded with the current time.
double	nextDouble() Returns a 64 bit uniformly distributed random number in the open unit interval (0.0,1.0) (excluding 0.0 and 1.0).
float	nextFloat() Returns a 32 bit uniformly distributed random number in the open unit interval (0.0f,1.0f) (excluding 0.0f and 1.0f).
abstract int	nextInt() Returns a 32 bit uniformly distributed random number in the closed interval [Integer.MIN_VALUE,Integer.MAX_VALUE] (including Integer.MIN_VALUE and Integer.MAX_VALUE);
long	nextLong() Returns a 64 bit uniformly distributed random number in the closed interval [Long.MIN_VALUE,Long.MAX_VALUE] (including Long.MIN_VALUE and Long.MAX_VALUE).
double	raw() Returns a 32 bit uniformly distributed random number in the open unit interval (0.0,1.0) (excluding 0.0 and 1.0).

Methods inherited from class edu.cornell.lassp.houle.RngPack.RandomSeedable

ClockSeed, ClockSeed

Methods inherited from class edu.cornell.lassp.houle.RngPack.RandomElement

choose, choose, gaussian, gaussian, powlaw, raw, raw, uniform

Methods inherited from class cern.colt.PersistentObject

clone

Methods inherited from class java.lang.Object

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

Method Detail

apply

public double apply(double dummy)

Equivalent to raw(). This has the effect that random engines can now be used as function objects, returning a random number upon function evaluation.

Specified by:

apply in interface DoubleFunction

Parameters:

dummy - argument passed to the function.

Returns:

the result of the function.

apply

public int apply(int dummy)

Equivalent to nextInt(). This has the effect that random engines can now be used as function objects, returning a random number upon function evaluation.

Specified by:

apply in interface IntFunction

Parameters:

dummy - argument passed to the function.

Returns:

the result of the function.

nextDouble

public double nextDouble()

Returns a 64 bit uniformly distributed random number in the open unit interval (0.0,1.0) (excluding 0.0 and 1.0).

nextFloat

public float nextFloat()

Returns a 32 bit uniformly distributed random number in the open unit interval (0.0f,1.0f) (excluding 0.0f and 1.0f).

nextInt

public abstract int nextInt()

Returns a 32 bit uniformly distributed random number in the closed interval [Integer.MIN_VALUE,Integer.MAX_VALUE] (including Integer.MIN_VALUE and Integer.MAX_VALUE);

nextLong

public long nextLong()

Returns a 64 bit uniformly distributed random number in the closed interval [Long.MIN_VALUE,Long.MAX_VALUE] (including Long.MIN_VALUE and Long.MAX_VALUE).

raw

public double raw()

Returns a 32 bit uniformly distributed random number in the open unit interval (0.0,1.0) (excluding 0.0 and 1.0).

Specified by:

raw in class RandomElement

Returns:

a random double in the range (0,1).

See Also:

RandomJava

makeDefault

public static RandomElement makeDefault()

Constructs and returns a new uniform random number engine seeded with the current time. Currently this is MersenneTwister.