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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:        UnuranDiscreteInt
 * Description:  create a discrete generator using UNURAN
 * 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.randvar;
import umontreal.iro.lecuyer.probdist.DiscreteDistributionInt;
import umontreal.iro.lecuyer.rng.RandomStream;


/**
 * This class permits one to create a discrete univariate
 * generator using UNURAN via its string API.
 * 
 */
public class UnuranDiscreteInt extends RandomVariateGenInt {

   private RandUnuran unuran = new RandUnuran();


   /**
    * Same as {@link #UnuranDiscreteInt UnuranDiscreteInt} (s, s, genStr).
    * 
    */
   public UnuranDiscreteInt (RandomStream s, String genStr) {
      if (s == null)
         throw new IllegalArgumentException ("mainStream must not be null.");

      unuran.mainStream = unuran.auxStream = s;
      unuran.init (genStr);
      if (!unuran.isDiscrete()) {
         unuran.close();
         throw new IllegalArgumentException ("not a discrete distribution");
      }
   }


   /**
    * Constructs a new discrete random number generator using
    *   the UNURAN generator specification string genStr,
    *   main stream s, and auxiliary stream aux.
    * 
    */
   public UnuranDiscreteInt (RandomStream s, RandomStream aux,
                             String genStr) {
      if (s == null)
         throw new IllegalArgumentException ("mainStream must not be null.");
      if (aux == null)
         throw new IllegalArgumentException ("auxStream must not be null.");

      unuran.mainStream = s;
      unuran.auxStream = aux;
      unuran.init (genStr);
      if (!unuran.isDiscrete()) {
         unuran.close();
         throw new IllegalArgumentException ("not a discrete distribution");
      }
   }


   public int nextInt() {
      if (unuran.nativeParams == 0)
         throw new IllegalStateException();
      return unuran.getRandDisc (unuran.mainStream.nextDouble(), unuran.nativeParams);
   }

   public void nextArrayOfInt (int[] v, int start, int n) {
      if (v == null || start < 0 || n < 0 || (start+n) > v.length)
         throw new IllegalArgumentException();
      if (unuran.unifArray == null || unuran.unifArray.length < n)
         unuran.unifArray = new double[n];
      if (unuran.mainStream != unuran.auxStream &&
         (unuran.unifAuxArray == null || unuran.unifAuxArray.length < n))
         unuran.unifAuxArray = new double[n];
      unuran.getRandDiscArray (unuran.nativeParams, unuran.unifArray,
                        unuran.unifAuxArray, v, start, n);
   }

   protected void finalize() {
      unuran.close();
   }

   public DiscreteDistributionInt getDistribution() { return null; }

   public RandomStream getStream() { return unuran.mainStream; }

   /**
    * Returns the auxiliary random number stream.
    * 
    */
   public RandomStream getAuxStream() {
      return unuran.auxStream;
   }
}