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.gene.tetrad.gene.history;
  
  import edu.cmu.tetrad.util.TetradSerializable;
  
  /**
   * <p>Implements a function from the previous time steps of a history array to
   * the getModel time step. The function is implemented factor by factor; for each
   * factor, the indexed connectivity specifies a specific set of parents
   * (IndexedParents) that the function is permitted to depend on for that factor;
   * the getLabel method returns the value for that set of parents in the
   * history. The update function may optionally be associated with an
   * IndexedLagGraph to provide information about the <i>intended</i> graphical
   * structure of the function (say, from a causal point of view). This
   * IndexedLagGraph gives information about the string names and order of the
   * factors and the number and order of the parents (IndexedParent's) for each
   * factor. This information should be encoded in the function itself, but there
   * is no requirement that the function be checked against the graph explicitly
   * to make sure the graph is actually implemented.</p>
   *
   * @author Joseph Ramsey jdramsey@andrew.cmu.edu
   */
  public interface UpdateFunction extends TetradSerializable {
      static final long serialVersionUID = 23L;
  
      /**
       * Returns the indexed lag graph, if one is available.
       */
      IndexedLagGraph getIndexedLagGraph();
  
      /**
       * Returns the value of the glass function for a given factor.
       *
       * @param factorIndex the index of the factor
       * @param history     the history array.
       * @return the value of the Glass function for this factor.
       */
      double getValue(int factorIndex, double[][] history);
  
      /**
       * Returns the number of factors in the history. This is used to set up the
       * initial history array.
       */
      int getNumFactors();
  
      /**
       * Returns the max lag of the gene history. This is used to set up the
       * initial history array.
       */
      int getMaxLag();
  }
  
  
  
  
  
  
  