Probability distributions implemented in CloudSim replaced by similar functions…

Probability distributions implemented in CloudSim replaced by similar functions from Apache math commons.

modules/cloudsim/src/main/java/org/cloudbus/cloudsim/distributions/ExponentialDistr.java

@@ -8,7 +8,7 @@
 
 package org.cloudbus.cloudsim.distributions;
 
-import java.util.Random;
+import org.apache.commons.math3.distribution.ExponentialDistribution;
 
 /**
  * An exponential number generator.
@@ -19,10 +19,8 @@ import java.util.Random;
 public class ExponentialDistr implements ContinuousDistribution {
 
 	/** The num gen. */
-	private final Random numGen;
+	private final ExponentialDistribution numGen;
 
-	/** The mean. */
-	private final double mean;
 
 	/**
 	 * Creates a new exponential number generator.
@@ -31,11 +29,8 @@ public class ExponentialDistr implements ContinuousDistribution {
 	 * @param mean the mean for the distribution.
 	 */
 	public ExponentialDistr(long seed, double mean) {
-		if (mean <= 0.0) {
-			throw new IllegalArgumentException("Mean must be greater than 0.0");
-		}
-		numGen = new Random(seed);
-		this.mean = mean;
+		this(mean);
+		numGen.reseedRandomGenerator(seed);
 	}
 
 	/**
@@ -44,11 +39,7 @@ public class ExponentialDistr implements ContinuousDistribution {
 	 * @param mean the mean for the distribution.
 	 */
 	public ExponentialDistr(double mean) {
-		if (mean <= 0.0) {
-			throw new IllegalArgumentException("Mean must be greated than 0.0");
-		}
-		numGen = new Random(System.currentTimeMillis());
-		this.mean = mean;
+		numGen = new ExponentialDistribution(mean);
 	}
 
 	/**
@@ -58,7 +49,7 @@ public class ExponentialDistr implements ContinuousDistribution {
 	 */
 	@Override
 	public double sample() {
-		return -mean * Math.log(numGen.nextDouble());
+		return numGen.sample();
 	}
 
 }

modules/cloudsim/src/main/java/org/cloudbus/cloudsim/distributions/GammaDistr.java

@@ -11,6 +11,8 @@ package org.cloudbus.cloudsim.distributions;
 
 import java.util.Random;
 
+import org.apache.commons.math3.distribution.GammaDistribution;
+
 /**
  * The Class GammaDistr.
  * 
@@ -20,13 +22,7 @@ import java.util.Random;
 public class GammaDistr implements ContinuousDistribution {
 
 	/** The num gen. */
-	private final Random numGen;
-
-	/** The alpha. */
-	private final int alpha;
-
-	/** The beta. */
-	private final double beta;
+	private final GammaDistribution numGen;
 
 	/**
 	 * Instantiates a new gamma distr.
@@ -35,14 +31,9 @@ public class GammaDistr implements ContinuousDistribution {
 	 * @param alpha the alpha
 	 * @param beta the beta
 	 */
-	public GammaDistr(Random seed, int alpha, double beta) {
-		if (alpha <= 0 || beta <= 0.0) {
-			throw new IllegalArgumentException("Alpha and beta must be greater than 0.0");
-		}
-
-		numGen = seed;
-		this.alpha = alpha;
-		this.beta = beta;
+	public GammaDistr(Random seed, int shape, double scale) {
+		this(shape, scale);
+		numGen.reseedRandomGenerator(seed.nextLong());
 	}
 
 	/**
@@ -51,14 +42,8 @@ public class GammaDistr implements ContinuousDistribution {
 	 * @param alpha the alpha
 	 * @param beta the beta
 	 */
-	public GammaDistr(int alpha, double beta) {
-		if (alpha <= 0 || beta <= 0.0) {
-			throw new IllegalArgumentException("Alpha and beta must be greater than 0.0");
-		}
-
-		numGen = new Random(System.currentTimeMillis());
-		this.alpha = alpha;
-		this.beta = beta;
+	public GammaDistr(int shape, double scale) {
+		numGen = new GammaDistribution(shape, scale);
 	}
 
 	/*
@@ -67,12 +52,7 @@ public class GammaDistr implements ContinuousDistribution {
 	 */
 	@Override
 	public double sample() {
-		double sum = 0.0;
-		for (int i = 0; i < alpha; i++) {
-			sum += Math.log(numGen.nextDouble());
-		}
-
-		return -beta * sum;
+		return numGen.sample();
 	}
 
 }

modules/cloudsim/src/main/java/org/cloudbus/cloudsim/distributions/LognormalDistr.java

@@ -10,6 +10,8 @@ package org.cloudbus.cloudsim.distributions;
 
 import java.util.Random;
 
+import org.apache.commons.math3.distribution.LogNormalDistribution;
+
 /**
  * The Class LognormalDistr.
  * 
@@ -18,14 +20,10 @@ import java.util.Random;
  */
 public class LognormalDistr implements ContinuousDistribution {
 
+	
 	/** The num gen. */
-	private final Random numGen;
-
-	/** The mean. */
-	private final double mean;
+	private final LogNormalDistribution numGen;
 
-	/** The dev. */
-	private final double dev;
 
 	/**
 	 * Instantiates a new lognormal distr.
@@ -34,14 +32,9 @@ public class LognormalDistr implements ContinuousDistribution {
 	 * @param mean the mean
 	 * @param dev the dev
 	 */
-	public LognormalDistr(Random seed, double mean, double dev) {
-		if (mean <= 0.0 || dev <= 0.0) {
-			throw new IllegalArgumentException("Mean and deviation must be greater than 0.0");
-		}
-
-		numGen = seed;
-		this.mean = mean;
-		this.dev = dev;
+	public LognormalDistr(Random seed, double shape, double scale) {
+		this(shape, scale);
+		numGen.reseedRandomGenerator(seed.nextLong());
 	}
 
 	/**
@@ -50,14 +43,8 @@ public class LognormalDistr implements ContinuousDistribution {
 	 * @param mean the mean
 	 * @param dev the dev
 	 */
-	public LognormalDistr(double mean, double dev) {
-		if (mean <= 0.0 || dev <= 0.0) {
-			throw new IllegalArgumentException("Mean and deviation must be greater than 0.0");
-		}
-
-		numGen = new Random(System.currentTimeMillis());
-		this.mean = mean;
-		this.dev = dev;
+	public LognormalDistr(double shape, double scale) {
+		numGen = new LogNormalDistribution(scale, shape);
 	}
 
 	/*
@@ -66,12 +53,7 @@ public class LognormalDistr implements ContinuousDistribution {
 	 */
 	@Override
 	public double sample() {
-		// generate a normal variate from a uniform variate
-		double n = Math.sqrt(-2 * Math.log(numGen.nextDouble()))
-				* Math.sin(2 * Math.PI * numGen.nextDouble());
-
-		// use it to generate the lognormal variate
-		return Math.pow(Math.E, mean + dev * n);
+		return numGen.sample();
 	}
 
 }

modules/cloudsim/src/main/java/org/cloudbus/cloudsim/distributions/ParetoDistr.java

@@ -11,6 +11,8 @@ package org.cloudbus.cloudsim.distributions;
 
 import java.util.Random;
 
+import org.apache.commons.math3.distribution.ParetoDistribution;
+
 /**
  * The Class ParetoDistr.
  * 
@@ -20,13 +22,7 @@ import java.util.Random;
 public class ParetoDistr implements ContinuousDistribution {
 
 	/** The num gen. */
-	private final Random numGen;
-
-	/** The shape. */
-	private final double shape;
-
-	/** The location. */
-	private final double location;
+	private final ParetoDistribution numGen;
 
 	/**
 	 * Instantiates a new pareto distr.
@@ -36,13 +32,8 @@ public class ParetoDistr implements ContinuousDistribution {
 	 * @param location the location
 	 */
 	public ParetoDistr(Random seed, double shape, double location) {
-		if (shape <= 0.0 || location <= 0.0) {
-			throw new IllegalArgumentException("Mean and deviation must be greater than 0.0");
-		}
-
-		numGen = seed;
-		this.shape = shape;
-		this.location = location;
+		this(shape, location);
+		numGen.reseedRandomGenerator(seed.nextLong());
 	}
 
 	/**
@@ -52,13 +43,7 @@ public class ParetoDistr implements ContinuousDistribution {
 	 * @param location the location
 	 */
 	public ParetoDistr(double shape, double location) {
-		if (shape <= 0.0 || location <= 0.0) {
-			throw new IllegalArgumentException("Mean and deviation must be greater than 0.0");
-		}
-
-		numGen = new Random(System.currentTimeMillis());
-		this.shape = shape;
-		this.location = location;
+		numGen = new ParetoDistribution(location, shape);
 	}
 
 	/*
@@ -67,7 +52,7 @@ public class ParetoDistr implements ContinuousDistribution {
 	 */
 	@Override
 	public double sample() {
-		return location / Math.pow(numGen.nextDouble(), 1 / shape);
+		return numGen.sample();
 	}
 
 }

modules/cloudsim/src/main/java/org/cloudbus/cloudsim/distributions/UniformDistr.java

@@ -10,6 +10,8 @@ package org.cloudbus.cloudsim.distributions;
 
 import java.util.Random;
 
+import org.apache.commons.math3.distribution.UniformRealDistribution;
+
 /**
  * A random number generator based on the Uniform distribution.
  * 
@@ -19,10 +21,7 @@ import java.util.Random;
 public class UniformDistr implements ContinuousDistribution {
 
 	/** The num gen. */
-	private final Random numGen;
-
-	/** The min. */
-	private final double mag, min;
+	private final UniformRealDistribution numGen;
 
 	/**
 	 * Creates new uniform distribution.
@@ -31,12 +30,7 @@ public class UniformDistr implements ContinuousDistribution {
 	 * @param max maximum value
 	 */
 	public UniformDistr(double min, double max) {
-		if (min >= max) {
-			throw new IllegalArgumentException("Maximum must be greater than the minimum.");
-		}
-		numGen = new Random();
-		mag = max - min;
-		this.min = min;
+		numGen = new UniformRealDistribution(min, max);
 	}
 
 	/**
@@ -47,13 +41,8 @@ public class UniformDistr implements ContinuousDistribution {
 	 * @param seed simulation seed to be used
 	 */
 	public UniformDistr(double min, double max, long seed) {
-		if (min >= max) {
-			throw new IllegalArgumentException("Maximum must be greater than the minimum.");
-		}
-
-		numGen = new Random(seed);
-		mag = max - min;
-		this.min = min;
+		this(min, max);
+		numGen.reseedRandomGenerator(seed);
 	}
 
 	/**
@@ -63,7 +52,7 @@ public class UniformDistr implements ContinuousDistribution {
 	 */
 	@Override
 	public double sample() {
-		return (numGen.nextDouble() * (mag)) + min;
+		return numGen.sample();
 	}
 
 	/**
@@ -89,7 +78,7 @@ public class UniformDistr implements ContinuousDistribution {
 	 * @param seed the new seed for the generator
 	 */
 	public void setSeed(long seed) {
-		numGen.setSeed(seed);
+		numGen.reseedRandomGenerator(seed);
 	}
 
 }
\ No newline at end of file

modules/cloudsim/src/main/java/org/cloudbus/cloudsim/distributions/WeibullDistr.java

@@ -11,6 +11,8 @@ package org.cloudbus.cloudsim.distributions;
 
 import java.util.Random;
 
+import org.apache.commons.math3.distribution.WeibullDistribution;
+
 /**
  * The Class WeibullDistr.
  * 
@@ -20,13 +22,7 @@ import java.util.Random;
 public class WeibullDistr implements ContinuousDistribution {
 
 	/** The num gen. */
-	private final Random numGen;
-
-	/** The alpha. */
-	private final double alpha;
-
-	/** The beta. */
-	private final double beta;
+	private final WeibullDistribution numGen;
 
 	/**
 	 * Instantiates a new weibull distr.
@@ -36,13 +32,8 @@ public class WeibullDistr implements ContinuousDistribution {
 	 * @param beta the beta
 	 */
 	public WeibullDistr(Random seed, double alpha, double beta) {
-		if (alpha <= 0.0 || beta <= 0.0) {
-			throw new IllegalArgumentException("Alpha and beta must be greater than 0.0");
-		}
-
-		numGen = seed;
-		this.alpha = alpha;
-		this.beta = beta;
+		this(alpha, beta);
+		numGen.reseedRandomGenerator(seed.nextLong());
 	}
 
 	/**
@@ -52,13 +43,7 @@ public class WeibullDistr implements ContinuousDistribution {
 	 * @param beta the beta
 	 */
 	public WeibullDistr(double alpha, double beta) {
-		if (alpha <= 0.0 || beta <= 0.0) {
-			throw new IllegalArgumentException("Alpha and beta must be greater than 0.0");
-		}
-
-		numGen = new Random(System.currentTimeMillis());
-		this.alpha = alpha;
-		this.beta = beta;
+		numGen = new WeibullDistribution(alpha, beta);
 	}
 
 	/*
@@ -67,7 +52,7 @@ public class WeibullDistr implements ContinuousDistribution {
 	 */
 	@Override
 	public double sample() {
-		return beta * Math.pow(-Math.log(numGen.nextDouble()), 1 / alpha);
+		return numGen.sample();
 	}
 
 }