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;
  
  /**
   * A pretend distribution that always returns the given value when
   * nextRandom() is called.
   *
   * @author Joseph Ramsey jdramsey@andrew.cmu.edu
   */
  public class SingleValue implements Distribution {
      static final long serialVersionUID = 23L;
  
      /**
       * @serial
       */
      private double value;
  
      //===========================CONSTRUCTORS===========================//
  
      /**
       * Constructs single value "distribution" using the given value.
       *
       * @param value A real number.
       */
      public SingleValue(double value) {
          this.value = value;
      }
  
      /**
       * Generates a simple exemplar of this class to test serialization.
       *
       * @return The exemplar.
       */
      public static SingleValue serializableInstance() {
          return new SingleValue(0.5);
      }
  
      public void setParameter(int index, double value) {
          if (index == 0) {
              this.value = value;
          } else {
              throw new IllegalArgumentException("Not a parameter index: " + index);
          }
      }
  
      public double getParameter(int index) {
          if (index == 0) {
              return this.value;
          } else {
              throw new IllegalArgumentException("Not a parameter index: " + index);
          }
      }
  
      public String getParameterName(int index) {
          if (index == 0) {
              return "Value";
          } else {
              throw new IllegalArgumentException("Not a parameter index: " + index);
          }
      }
  
      public int getNumParameters() {
          return 1;
      }
  
      //============================PUBLIC METHODS========================//
  
      /**
       * @return the value that was set.
       */
      public double nextRandom() {
          return getValue();
      }
  
      public String toString() {
          return "[" + getValue() + "]";
      }
  
      private double getValue() {
          return value;
      }
  
  
      public String getName() {
          return "Single Value";
      }
  }
  
  
  
  
  
  