content: // ===============================================================================
  // Authors: AFRL/RQQD
  // Organization: Air Force Research Laboratory, Aerospace Systems Directorate, Power and Control Division
  // 
  // Copyright (c) 2017 Government of the United State of America, as represented by
  // the Secretary of the Air Force.  No copyright is claimed in the United States under
  // Title 17, U.S. Code.  All Other Rights Reserved.
  // ===============================================================================
  
  /*
   * GRAL: GRAphing Library for Java(R)
   *
   * (C) Copyright 2009-2013 Erich Seifert <dev[at]erichseifert.de>,
   * Michael Seifert <mseifert[at]error-reports.org>
   *
   * This file is part of GRAL.
   *
   * GRAL is free software: you can redistribute it and/or modify
   * it under the terms of the GNU Lesser General Public License as published by
   * the Free Software Foundation, either version 3 of the License, or
   * (at your option) any later version.
   *
   * GRAL 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 Lesser General Public License for more details.
   *
   * You should have received a copy of the GNU Lesser General Public License
   * along with GRAL.  If not, see <http://www.gnu.org/licenses/>.
   */
  package de.erichseifert.gral.util;
  
  import java.io.Serializable;
  import java.util.Iterator;
  
  /**
   * Class that calculates the values of the Halton sequence.
   */
  public class HaltonSequence implements Iterator<Double>, Serializable {
  	/** Version id for serialization. */
  	private static final long serialVersionUID = 7466395251522942013L;
  
  	/** Base. */
  	private final int base;
  	/** Current count. */
  	private long c;
  
  	/**
  	 * Creates a new HaltonSequence object to the base of two.
  	 */
  	public HaltonSequence() {
  		this(2);
  	}
  
  	/**
  	 * Creates a new instance with the specified base.
  	 * @param base Base value.
  	 */
  	public HaltonSequence(int base) {
  		this.base = base;
  	}
  
      /**
       * Returns whether the iteration has more elements. This means it returns
       * {@code true} if {@code next} would return an element rather
       * than throwing an exception.
       * @return {@code true} if the iterator has more elements.
       */
  	public boolean hasNext() {
  		return true;
  	}
  
      /**
       * Returns the next element in the iteration.
       * @return the next element in the iteration.
       */
  	public Double next() {
  		long i, digit;
  		double h, step;
  
  		if (++c == Long.MAX_VALUE) {
  			c = 0;
  		}
  
  		i = c;
  		h = 0.0;
  		step = 1.0 / base;
  
  		while (i > 0) {
  			digit = i % base;
  		    h += digit * step;
  		    i = (i - digit) / base;
  		    step /= base;
  		}
  
  		return h;
  	}
  
  	/**
  	 * Stub method to fulfill {@code Iterator} interface.
  	 */
  	public void remove() {
  	}
  
  }
  