001/* ===========================================================
002 * JFreeChart : a free chart library for the Java(tm) platform
003 * ===========================================================
004 *
005 * (C) Copyright 2000-2007, by Object Refinery Limited and Contributors.
006 *
007 * Project Info:  http://www.jfree.org/jfreechart/index.html
008 *
009 * This library is free software; you can redistribute it and/or modify it 
010 * under the terms of the GNU Lesser General Public License as published by 
011 * the Free Software Foundation; either version 2.1 of the License, or 
012 * (at your option) any later version.
013 *
014 * This library is distributed in the hope that it will be useful, but 
015 * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY 
016 * or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public 
017 * License for more details.
018 *
019 * You should have received a copy of the GNU Lesser General Public
020 * License along with this library; if not, write to the Free Software
021 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, 
022 * USA.  
023 *
024 * [Java is a trademark or registered trademark of Sun Microsystems, Inc. 
025 * in the United States and other countries.]
026 *
027 * --------------------
028 * PowerFunction2D.java
029 * --------------------
030 * (C) Copyright 2002-2007, by Object Refinery Limited.
031 *
032 * Original Author:  David Gilbert (for Object Refinery Limited);
033 * Contributor(s):   -;
034 *
035 * Changes:
036 * --------
037 * 01-Oct-2002 : Version 1 (DG);
038 *
039 */
040
041package org.jfree.data.function;
042
043
044/**
045 * A function of the form y = a * x ^ b.
046 */
047public class PowerFunction2D implements Function2D {
048
049    /** The 'a' coefficient. */
050    private double a;
051
052    /** The 'b' coefficient. */
053    private double b;
054
055    /**
056     * Creates a new power function.
057     *
058     * @param a  the 'a' coefficient.
059     * @param b  the 'b' coefficient.
060     */
061    public PowerFunction2D(double a, double b) {
062        this.a = a;
063        this.b = b;
064    }
065
066    /**
067     * Returns the value of the function for a given input ('x').
068     *
069     * @param x  the x-value.
070     *
071     * @return The value.
072     */
073    public double getValue(double x) {
074        return this.a * Math.pow(x, this.b);
075    }
076
077}