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.algorithm.urchin;
  
  import edu.cmu.tetrad.util.RandomUtil;
  
  public class NbGeneAnd extends AbstractNbComponent {
      public NbGeneAnd(double factor, double power, NbComponent[] parents,
              int[] inhibitExcite, String name, double sd) {
          super(factor, power, parents, inhibitExcite, name);
      }
  
      public void update() {
          //System.out.println("Updating " + name);
          double product = 1.0;
          for (int i = 0; i < getNparents(); i++) {
              double v = getParents()[i].getValue();
              if (getInhibitExcite()[i] > 0) {
                  product *= v / (v + 1.0);
              }
              else {
                  product *= (1.0 - (v / (v + 1.0)));
              }
          }
          setValue(product * getFactor());
  
          if (getSd() == 0.0) {
              return;
          }
          else {
              double r = 1.0 +
                      RandomUtil.getInstance().nextNormal(0, 1) * getSd();
              setValue(getValue() * r);
          }
      }
  }
  
  
  
  
  
  