de.uka.ipd.sdq.simucomframework

Class SimuComDefaultRandomNumberGenerator

java.lang.Object

de.uka.ipd.sdq.simucomframework.SimuComDefaultRandomNumberGenerator

All Implemented Interfaces:

de.uka.ipd.sdq.probfunction.math.IRandomGenerator

public class SimuComDefaultRandomNumberGenerator
extends Object
implements de.uka.ipd.sdq.probfunction.math.IRandomGenerator

SimuComDefaultRandomNumberGenerator generates random numbers in a separate thread. SimuComDefaultRandomNumberGenerator currently implements the interface for random numbers needed by the prob function package. However, internally it relies on a random stream implementing the RandomStream interface from JSS. SimuComDefaultRandomNumberGenerator implements RandomStream as the functions like LogNormDistFunction and NormDistFunction in package de.uka.ipd.sdq.simucomframework.variables.functions. This class is optimized for multi-cores, thus speeding up simulation significantly for at least two cores. Here everything related to random numbers in SimuCom should be then localised, especially seed initialisation and the multi-threading stuff (which was - as always - deadlock prone while implementing). Also it locates the dependency to the [0..1] random number generator to a single place in the source (remember this needs to be changed to get away from GPL code...).

Author:

Steffen Becker

Constructor Summary

Constructors

Constructor and Description
SimuComDefaultRandomNumberGenerator(long[] randomSeed)

Method Summary

Modifier and Type	Method and Description
void	dispose()
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.
double	random() Returns a (pseudo)random number from the uniform distribution over the interval (0, 1), using this stream, after advancing its state by one step.
void	resetNextSubstream() does nothing because this implementation does not support any substreams
void	resetStartStream() does nothing because this implementation does not support any substreams
void	resetStartSubstream() does nothing because this implementation does not support any substreams

Methods inherited from class java.lang.Object

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

Constructor Detail

SimuComDefaultRandomNumberGenerator

public SimuComDefaultRandomNumberGenerator(long[] randomSeed)

Method Detail

random

public double random()

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. This method takes a previously generated random number from the asynchronously running generator thread.

Specified by:

random in interface de.uka.ipd.sdq.probfunction.math.IRandomGenerator

dispose

public void dispose()

Specified by:

dispose in interface de.uka.ipd.sdq.probfunction.math.IRandomGenerator

nextArrayOfDouble

public 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. (doc from 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

nextArrayOfInt

public 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. (Calls nextInt n times.) (doc from 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

nextDouble

public 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. The generators programmed in SSJ never return the values 0 or 1. Calls random() which takes a previously generated random number from the asynchronously running generator thread.

nextInt

public 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. (Calls nextDouble once.) Copied from RandomStreamBase.

Parameters:

i - - smallest integer that can be generated

j - - greatest integer that can be generated

resetNextSubstream

public void resetNextSubstream()

does nothing because this implementation does not support any substreams

resetStartStream

public void resetStartStream()

does nothing because this implementation does not support any substreams

resetStartSubstream

public void resetStartSubstream()

does nothing because this implementation does not support any substreams