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SSJ is a Java library for stochastic simulation, developed under the direction of Pierre L'Ecuyer, in the Département d'Informatique et de Recherche Opérationnelle (DIRO), at the Université de Montréal. It provides facilities for generating uniform and nonuniform random variates, computing different measures related to probability distributions, performing goodness-of-fit tests, applying quasi-Monte Carlo methods, collecting (elementary) statistics, and programming discrete-event simulations with both events and processes.

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/*
 * Class:        RandomStart
 * Description:  Randomizes a sequence with a random starting point
 * Environment:  Java
 * Software:     SSJ 
 * Copyright (C) 2001  Pierre L'Ecuyer and Université de Montréal
 * Organization: DIRO, Université de Montréal
 * @author       
 * @since

 * SSJ is free software: you can redistribute it and/or modify it under
 * the terms of the GNU General Public License (GPL) as published by the
 * Free Software Foundation, either version 3 of the License, or
 * any later version.

 * SSJ is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.

 * A copy of the GNU General Public License is available at
   GPL licence site.
 */

package umontreal.iro.lecuyer.hups;

 import umontreal.iro.lecuyer.rng.RandomStream;
 import java.lang.IllegalArgumentException;


/**
 * This class implements a
 * {@link umontreal.iro.lecuyer.hups.PointSetRandomization PointSetRandomization}
 * that randomizes a sequence with a random starting point.
 * The point set must be an instance of 
 * {@link umontreal.iro.lecuyer.hups.HaltonSequence HaltonSequence} or an
 * {@link java.lang.IllegalArgumentException IllegalArgumentException} is thrown.
 * For now, only the Halton sequence is allowed, but there may be others
 * later.
 * 
 */
public class RandomStart implements PointSetRandomization  {

   protected RandomStream stream;



   /**
    * Empty constructor.
    * 
    */
   public RandomStart()  {
   }
   


   /**
    * Sets internal variable stream to the given
    *    stream.
    * 
    * @param stream stream to use in the randomization
    * 
    */
   public RandomStart (RandomStream stream)  {
       this.stream = stream;
   }
   


   /**
    * This method calls
    *    {@link umontreal.iro.lecuyer.hups.HaltonSequence#init(double[]) init}.
    *    If p is not a
    *    {@link umontreal.iro.lecuyer.hups.HaltonSequence HaltonSequence}, an
    * {@link java.lang.IllegalArgumentException IllegalArgumentException} is thrown.
    * 
    * @param p Point set to randomize
    * 
    * 
    */
   public void randomize (PointSet p)  {
      if (p instanceof HaltonSequence) {
         double[] x0 = new double[p.getDimension()];
         stream.nextArrayOfDouble(x0, 0, x0.length);
         ((HaltonSequence)p).setStart (x0);
      } else {
         throw new IllegalArgumentException("RandomStart" +
                     " can only randomize a HaltonSequence");
      }
   }
   


   /**
    * Sets the internal
    *    {@link umontreal.iro.lecuyer.rng.RandomStream RandomStream} to
    *    stream.
    * 
    * @param stream stream to use in the randomization
    * 
    * 
    */
   public void setStream (RandomStream stream)  {
      this.stream = stream;
   } 


   /**
    * Returns the internal
    *    {@link umontreal.iro.lecuyer.rng.RandomStream RandomStream}.
    * 
    * @return stream used in the randomization
    * 
    */
   public RandomStream getStream()  {
      return stream;
   } 

}