Source for org.jfree.formula.operators.PowerOperator

   1: /**
   2:  * =========================================
   3:  * LibFormula : a free Java formula library
   4:  * =========================================
   5:  *
   6:  * Project Info:  http://reporting.pentaho.org/libformula/
   7:  *
   8:  * (C) Copyright 2006-2007, by Pentaho Corporation and Contributors.
   9:  *
  10:  * This library is free software; you can redistribute it and/or modify it under the terms
  11:  * of the GNU Lesser General Public License as published by the Free Software Foundation;
  12:  * either version 2.1 of the License, or (at your option) any later version.
  13:  *
  14:  * This library is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY;
  15:  * without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
  16:  * See the GNU Lesser General Public License for more details.
  17:  *
  18:  * You should have received a copy of the GNU Lesser General Public License along with this
  19:  * library; if not, write to the Free Software Foundation, Inc., 59 Temple Place, Suite 330,
  20:  * Boston, MA 02111-1307, USA.
  21:  *
  22:  * [Java is a trademark or registered trademark of Sun Microsystems, Inc.
  23:  * in the United States and other countries.]
  24:  *
  25:  *
  26:  * ------------
  27:  * $Id: PowerOperator.java 2752 2007-04-10 14:10:41Z taqua $
  28:  * ------------
  29:  * (C) Copyright 2006-2007, by Pentaho Corporation.
  30:  */
  31: package org.jfree.formula.operators;
  32: 
  33: import org.jfree.formula.EvaluationException;
  34: 
  35: /**
  36:  * This has to be implemented manually if we want to support arbitary precision.
  37:  * Damn, do I have to implement the logarithm computation as well? For now:
  38:  * Ignore that and use doubles!
  39:  *
  40:  * @author Thomas Morgner
  41:  */
  42: public class PowerOperator extends AbstractNumericOperator
  43: {
  44:   public PowerOperator()
  45:   {
  46:   }
  47: 
  48:   protected Number evaluate(final Number number1, final Number number2) throws EvaluationException
  49:   {
  50:     final double result = Math.pow(number1.doubleValue(), number2.doubleValue());
  51:     return new Double(result);
  52:   }
  53: 
  54:   public int getLevel()
  55:   {
  56:     return 0;
  57:   }
  58: 
  59:   public String toString()
  60:   {
  61:     return "POW";
  62:   }
  63: 
  64:   public boolean isLeftOperation()
  65:   {
  66:     return false;
  67:   }
  68: 
  69:   /**
  70:    * Defines, whether the operation is associative. For associative operations,
  71:    * the evaluation order does not matter, if the operation appears more than
  72:    * once in an expression, and therefore we can optimize them a lot better than
  73:    * non-associative operations (ie. merge constant parts and precompute them
  74:    * once).
  75:    *
  76:    * @return true, if the operation is associative, false otherwise
  77:    */
  78:   public boolean isAssociative()
  79:   {
  80:     return false;
  81:   }
  82: 
  83: }