/* ===========================================================
* JFreeChart : a free chart library for the Java(tm) platform
* ===========================================================
*
* (C) Copyright 2000-2011, 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.]
*
* -------------------
* LineFunction2D.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 in the form y = a + bx.
*/
public class LineFunction2D implements Function2D, Serializable {
/** The intercept. */
private double a;
/** The slope of the line. */
private double b;
/**
* Constructs a new line function.
*
* @param a the intercept.
* @param b the slope.
*/
public LineFunction2D(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 getIntercept() {
return this.a;
}
/**
* Returns the 'b' coefficient that was specified in the constructor.
*
* @return The 'b' coefficient.
*
* @since 1.0.14
*/
public double getSlope() {
return this.b;
}
/**
* Returns the function value.
*
* @param x the x-value.
*
* @return The value.
*/
public double getValue(double x) {
return this.a + this.b * x;
}
/**
* Tests this function for equality with an arbitrary object.
*
* @param obj the object (<code>null</code> permitted).
*
* @return A boolean.
*/
public boolean equals(Object obj) {
if (!(obj instanceof LineFunction2D)) {
return false;
}
LineFunction2D that = (LineFunction2D) 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.
*/
public int hashCode() {
int result = 29;
result = HashUtilities.hashCode(result, this.a);
result = HashUtilities.hashCode(result, this.b);
return result;
}
}
|