LatinHypercube.java

/*
 * Class:        LatinHypercube
 * Description:  
 * Environment:  Java
 * Software:     SSJ 
 * Copyright (C) 2001  Pierre L'Ecuyer and Universite de Montreal
 * Organization: DIRO, Universite de Montreal
 * @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
   <a href="http://www.gnu.org/licenses">GPL licence site</a>.
 */
package umontreal.ssj.hups;
 
import umontreal.ssj.rng.RandomStream;
import umontreal.ssj.rng.*;

public class LatinHypercube extends CachedPointSet {
 
   protected double delta; // Size of divisions in each dimension, = 1/n

   public LatinHypercube(int n, int dim) {
      this.dim = dim;
      delta = 1.0 / n;
      numPoints = n;
      x = new double[numPoints][dim];
   }

   public void randomize(RandomStream stream) {
      int[] permutation = new int[numPoints];
      // RandomPermutation.init (permutation, numPoints);
      // Generate one random number uniformly in each interval for first coord.
      for (int i = 0; i < numPoints; i++) {
         permutation[i] = i;
         x[i][0] = (i + stream.nextDouble()) * delta;
      }
      for (int j = 1; j < dim; j++) {
         RandomPermutation.shuffle(permutation, stream);
         // Generate one random number uniformly in each interval for coord. j.
         for (int i = 0; i < numPoints; i++)
            x[permutation[i]][j] = (i + stream.nextDouble()) * delta;
      }
   }

   public void addRandomShift(int fromDim, int toDim, RandomStream stream) {
      randomize(stream);
   }

   public void randomize(PointSetRandomization rand) {
      randomize(rand.getStream());
   }
 
   public String toString() {
      return "LatinHypercube: LHS over the unit cube in " + dim + "dimensions.";
   }
}