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JFreeChart is a class library, written in Java, for generating charts.
Utilising the Java2D APIs, it currently supports bar charts, pie charts,
line charts, XY-plots and time series plots.
/* ===========================================================
* JFreeChart : a free chart library for the Java(tm) platform
* ===========================================================
*
* (C) Copyright 2000-2013, by Object Refinery Limited and Contributors.
*
* Project Info: http://www.jfree.org/jfreechart/index.html
*
* This library is free software; you can redistribute it and/or modify it
* under the terms of the GNU Lesser General Public License as published by
* the Free Software Foundation; either version 2.1 of the License, or
* (at your option) any later version.
*
* This library 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 Lesser General Public
* License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301,
* USA.
*
* [Oracle and Java are registered trademarks of Oracle and/or its affiliates.
* Other names may be trademarks of their respective owners.]
*
* --------------------
* PowerFunction2D.java
* --------------------
* (C) Copyright 2002-2009, by Object Refinery Limited.
*
* Original Author: David Gilbert (for Object Refinery Limited);
* Contributor(s): -;
*
* Changes:
* --------
* 01-Oct-2002 : Version 1 (DG);
* 28-May-2009 : Added accessor methods for co-efficients, implemented
* equals() and hashCode(), and added Serialization support (DG);
*
*/
package org.jfree.data.function;
import java.io.Serializable;
import org.jfree.chart.HashUtilities;
/**
* A function of the form y = a * x ^ b.
*/
public class PowerFunction2D implements Function2D, Serializable {
/** The 'a' coefficient. */
private double a;
/** The 'b' coefficient. */
private double b;
/**
* Creates a new power function.
*
* @param a the 'a' coefficient.
* @param b the 'b' coefficient.
*/
public PowerFunction2D(double a, double b) {
this.a = a;
this.b = b;
}
/**
* Returns the 'a' coefficient that was specified in the constructor.
*
* @return The 'a' coefficient.
*
* @since 1.0.14
*/
public double getA() {
return this.a;
}
/**
* Returns the 'b' coefficient that was specified in the constructor.
*
* @return The 'b' coefficient.
*
* @since 1.0.14
*/
public double getB() {
return this.b;
}
/**
* Returns the value of the function for a given input ('x').
*
* @param x the x-value.
*
* @return The value.
*/
@Override
public double getValue(double x) {
return this.a * Math.pow(x, this.b);
}
/**
* Tests this function for equality with an arbitrary object.
*
* @param obj the object (null permitted).
*
* @return A boolean.
*/
@Override
public boolean equals(Object obj) {
if (!(obj instanceof PowerFunction2D)) {
return false;
}
PowerFunction2D that = (PowerFunction2D) obj;
if (this.a != that.a) {
return false;
}
if (this.b != that.b) {
return false;
}
return true;
}
/**
* Returns a hash code for this instance.
*
* @return A hash code.
*/
@Override
public int hashCode() {
int result = 29;
result = HashUtilities.hashCode(result, this.a);
result = HashUtilities.hashCode(result, this.b);
return result;
}
}