DiscShift2Lattice.java

/*
 * Class:        DiscShift2Lattice
 * Description:  computes a discrepancy for the randomly shifted points of a
                 lattice
 * Environment:  Java
 * Software:     SSJ 
 * Copyright (C) 2001  Pierre L'Ecuyer and Universite de Montreal
 * Organization: DIRO, Universite de Montreal
 * @author       Richard Simard
 * @since        January 2009
 
 * 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.discrepancy;
 
import umontreal.ssj.hups.Rank1Lattice;

public class DiscShift2Lattice extends DiscShift2 {

   public DiscShift2Lattice(double[][] points, int n, int s) {
      super(points, n, s);
   }

   public DiscShift2Lattice(double[][] points, int n, int s, double[] gamma) {
      super(points, n, s, gamma);
   }

   public DiscShift2Lattice(int n, int s, double[] gamma) {
      super(n, s, gamma);
   }

   public DiscShift2Lattice(Rank1Lattice set) {
      super(set);
   }

   public DiscShift2Lattice() {
   }

   public double compute(double[][] points, int n, int s) {
      setONES(s);
      return compute(points, n, s, ONES);
   }

   public double compute(double[][] points, int n, int s, double[] gamma) {
      double[] C1 = new double[s];
      double[] C2 = new double[s];
      setC(C1, C2, gamma, s);
 
      double sum = 0.0;
      for (int i = 0; i < n; ++i) {
         double prod = 1.0;
         for (int r = 0; r < s; ++r) {
            double u = points[i][r];
            double pol1 = u * (u - 1.0) + UNSIX; // Bernoulli(2, u)
            double pol2 = ((u - 2.0) * u + 1.0) * u * u - UNTRENTE; // Bernoulli(4,h)
            prod *= 1.0 + C1[r] * pol1 - C2[r] * pol2;
         }
         sum += prod;
      }
      double disc = sum / n - 1.0;
      if (disc < 0.0)
         return -1.0;
      return Math.sqrt(disc);
   }

   public double compute(double[] T, int n) {
      return compute(T, n, 1.);
   }

   public double compute(double[] T, int n, double gamma) {
      double[] C = setC(gamma);
      double C1 = C[0];
      double C2 = C[1];
      double pol1;
      double pol2;
 
      double sum = 0.0;
      for (int i = 0; i < n; ++i) {
         double u = T[i];
         pol1 = u * (u - 1.0) + UNSIX; // Bernoulli(2, u)
         pol2 = ((u - 2.0) * u + 1.0) * u * u - UNTRENTE; // Bernoulli(4,h)
         sum += C1 * pol1 - C2 * pol2;
      }
      double disc = sum / n;
      if (disc <= 0.0)
         return 0.0;
      return Math.sqrt(disc);
   }
 
}