code: ///////////////////////////////////////////////////////////////////////////////
  // For information as to what this class does, see the Javadoc, below.       //
  // Copyright (C) 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006,       //
  // 2007, 2008, 2009, 2010, 2014, 2015 by Peter Spirtes, Richard Scheines, Joseph   //
  // Ramsey, and Clark Glymour.                                                //
  //                                                                           //
  // This program is free software; you can redistribute it and/or modify      //
  // it under the terms of the GNU General Public License as published by      //
  // the Free Software Foundation; either version 2 of the License, or         //
  // (at your option) any later version.                                       //
  //                                                                           //
  // This program 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.                              //
  //                                                                           //
  // You should have received a copy of the GNU General Public License         //
  // along with this program; if not, write to the Free Software               //
  // Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA //
  ///////////////////////////////////////////////////////////////////////////////
  
  package edu.cmu.tetrad.util.dist;
  
  import edu.cmu.tetrad.util.NumberFormatUtil;
  import edu.cmu.tetrad.util.RandomUtil;
  
  import java.io.IOException;
  import java.io.ObjectInputStream;
  import java.text.NumberFormat;
  
  /**
   * For given a, b (a < b), returns a point chosen uniformly from [a, b]. The
   * parameters are 0 = a, 1 = b.
   *
   * @author Joseph Ramsey jdramsey@andrew.cmu.edu
   */
  public class Uniform implements Distribution {
      static final long serialVersionUID = 23L;
  
      /**
       * The lower bound of the range from which numbers are drawn uniformly.
       *
       * @serial
       */
      private double a;
  
      /**
       * The upper bound of the range from which numbers are drawn uniformly.
       *
       * @serial
       */
      private double b;
  
      //=========================CONSTRUCTORS===========================//
  
      public Uniform(double a, double b) {
          if (!(a <= b)) {
              throw new IllegalArgumentException("a must be less than or equal to b.");
          }
  
          this.a = a;
          this.b = b;
      }
  
      /**
       * Generates a simple exemplar of this class to test serialization.
       */
      public static Uniform serializableInstance() {
          return new Uniform(0, 1);
      }
  
      //=========================PUBLIC METHODS=========================//
  
      /**
       * Sets the value of the i'th parameter.
       */
      public void setParameter(int index, double value) {
          if (index == 0 && value < b) {
              a = value;
          } else if (index == 1 && value > a) {
              b = value;
          } else {
              throw new IllegalArgumentException("Illegal value for parameter " +
                      index + ": " + value);
          }
      }
  
      /**
       * @return the value of the ith parameter.
       */
      public double getParameter(int index) {
          if (index == 0) {
              return a;
          } else if (index == 1) {
              return b;
          } else {
              throw new IllegalArgumentException("Illegal index: " + index);
          }
      }
  
      public String getParameterName(int index) {
          if (index == 0) {
              return "Lower Bound";
          } else if (index == 1) {
              return "Upper Bound";
          } else {
              throw new IllegalArgumentException("Not a parameter index: " + index);
          }
      }
  
      /**
       * @return the number of parameters = 2.
       */
      public int getNumParameters() {
          return 2;
      }
  
      /**
       * @return the next random sample from the distribution.
       */
      public double nextRandom() {
          return RandomUtil.getInstance().nextUniform(a, b);
      }
  
  
      public String getName() {
          return "Uniform";
      }
  
      public String toString() {
          NumberFormat nf = NumberFormatUtil.getInstance().getNumberFormat();
          return "U(" + nf.format(getParameter(0)) + ", " + nf.format(getParameter(1)) + ")";
      }
  
      //========================PRIVATE METHODS===========================//
  
      /**
       * Adds semantic checks to the default deserialization method. This method
       * must have the standard signature for a readObject method, and the body of
       * the method must begin with "s.defaultReadObject();". Other than that, any
       * semantic checks can be specified and do not need to stay the same from
       * version to version. A readObject method of this form may be added to any
       * class, even if Tetrad sessions were previously saved out using a version
       * of the class that didn't include it. (That's what the
       * "s.defaultReadObject();" is for. See J. Bloch, Effective Java, for help.
       *
       * @throws java.io.IOException
       * @throws ClassNotFoundException
       */
      private void readObject(ObjectInputStream s)
              throws IOException, ClassNotFoundException {
          s.defaultReadObject();
  
          if (a >= b) {
              throw new IllegalStateException();
          }
      }
  }
  
  
  
  
  
  