51 lines
1.3 KiB
Java
51 lines
1.3 KiB
Java
/*
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* Title: EdgeCloudSim - Poisson Distribution
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*
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* Description: Wrapper class for colt Poisson Distribution
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*
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* Licence: GPL - http://www.gnu.org/copyleft/gpl.html
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* Copyright (c) 2017, Bogazici University, Istanbul, Turkey
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*/
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package edu.boun.edgecloudsim.utils;
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import java.util.Date;
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import java.util.concurrent.TimeUnit;
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import cern.jet.random.Poisson;
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import cern.jet.random.engine.MersenneTwister;
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import cern.jet.random.engine.RandomEngine;
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public class PoissonDistr {
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Poisson poisson;
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RandomEngine engine;
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/**
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* Creates a new exponential number generator.
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*
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* @param mean the mean for the distribution.
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*/
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public PoissonDistr(double mean) {
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engine = new MersenneTwister(new Date());
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poisson = new Poisson(mean, engine);
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//always sleep for some milliseconds in order not to have same seed for iterative PoissonDistr construction
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try {
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TimeUnit.MILLISECONDS.sleep(10);
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} catch (InterruptedException e) {
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SimLogger.printLine("impossible is occurred! Poisson random number cannot be created!");
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e.printStackTrace();
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System.exit(1);
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}
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}
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/**
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* Generate a new random number.
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*
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* @return the next random number in the sequence
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*/
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public double sample() {
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return poisson.nextDouble();
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}
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}
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