KickJava   Java API By Example, From Geeks To Geeks.

Java > Open Source Codes > org > jfree > data > function > NormalDistributionFunction2D


1 /* ===========================================================
2  * JFreeChart : a free chart library for the Java(tm) platform
3  * ===========================================================
4  *
5  * (C) Copyright 2000-2005, by Object Refinery Limited and Contributors.
6  *
7  * Project Info: http://www.jfree.org/jfreechart/index.html
8  *
9  * This library is free software; you can redistribute it and/or modify it
10  * under the terms of the GNU Lesser General Public License as published by
11  * the Free Software Foundation; either version 2.1 of the License, or
12  * (at your option) any later version.
13  *
14  * This library is distributed in the hope that it will be useful, but
15  * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
16  * or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public
17  * License for more details.
18  *
19  * You should have received a copy of the GNU Lesser General Public
20  * License along with this library; if not, write to the Free Software
21  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301,
22  * USA.
23  *
24  * [Java is a trademark or registered trademark of Sun Microsystems, Inc.
25  * in the United States and other countries.]
26  *
27  * ---------------------------------
28  * NormalDistributionFunction2D.java
29  * ---------------------------------
30  * (C)opyright 2004, 2005, by Object Refinery Limited.
31  *
32  * Original Author: David Gilbert (for Object Refinery Limited);
33  * Contributor(s): -;
34  *
35  * $Id: NormalDistributionFunction2D.java,v 1.3.2.2 2005/11/21 10:58:33 mungady Exp $
36  *
37  * Changes
38  * -------
39  * 25-May-2004 : Version 1 (DG);
40  * 21-Nov-2005 : Added getters for the mean and standard deviation (DG);
41  *
42  */
43
44 package org.jfree.data.function;
45
46 /**
47  * A normal distribution function.
48  */
49 public class NormalDistributionFunction2D implements Function2D {
50
51     /** The mean. */
52     private double mean;
53
54     /** The standard deviation. */
55     private double std;
56
57     /**
58      * Constructs a new normal distribution function.
59      *
60      * @param mean the mean.
61      * @param std the standard deviation.
62      */
63     public NormalDistributionFunction2D(double mean, double std) {
64         this.mean = mean;
65         this.std = std;
66     }
67     
68     /**
69      * Returns the mean for the function.
70      *
71      * @return The mean.
72      */
73     public double getMean() {
74         return this.mean;
75     }
76     
77     /**
78      * Returns the standard deviation for the function.
79      *
80      * @return The standard deviation.
81      */
82     public double getStandardDeviation() {
83         return this.std;
84     }
85
86     /**
87      * Returns the function value.
88      *
89      * @param x the x-value.
90      *
91      * @return The value.
92      */
93     public double getValue(double x) {
94         return Math.exp(-1.0 * (x - this.mean) * (x - this.mean)
95                 / (2 * this.std * this.std)) / Math.sqrt(2 * Math.PI
96                 * this.std * this.std);
97     }
98
99 }
100
Popular Tags