KickJava   Java API By Example, From Geeks To Geeks.

Java > Open Source Codes > org > apache > commons > math > distribution > PoissonDistribution


1 /*
2  * Copyright 2004 The Apache Software Foundation.
3  *
4  * Licensed under the Apache License, Version 2.0 (the "License");
5  * you may not use this file except in compliance with the License.
6  * You may obtain a copy of the License at
7  *
8  * http://www.apache.org/licenses/LICENSE-2.0
9  *
10  * Unless required by applicable law or agreed to in writing, software
11  * distributed under the License is distributed on an "AS IS" BASIS,
12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13  * See the License for the specific language governing permissions and
14  * limitations under the License.
15  */
16 package org.apache.commons.math.distribution;
17
18 import org.apache.commons.math.MathException;
19
20 /**
21  * Interface representing the Poisson Distribution.
22  *
23  * <p>
24  * References:
25  * <ul>
26  * <li><a HREF="http://mathworld.wolfram.com/PoissonDistribution.html">
27  * Poisson distribution</a></li>
28  * </ul>
29  * </p>
30  *
31  * @version $Revision$ $Date: 2005-02-26 05:11:52 -0800 (Sat, 26 Feb 2005) $
32  */
33 public interface PoissonDistribution extends IntegerDistribution {
34
35     /**
36      * Get the mean for the distribution.
37      *
38      * @return the mean for the distribution.
39      */
40     public double getMean();
41
42     /**
43      * Set the mean for the distribution.
44      * The parameter value must be positive; otherwise an
45      * <code>IllegalArgument</code> is thrown.
46      *
47      * @param p the mean
48      * @throws IllegalArgumentException if p &le; 0
49      */
50     public void setMean(double p);
51
52     /**
53      * Calculates the Poisson distribution function using a normal approximation.
54      *
55      * @param x the upper bound, inclusive
56      * @return the distribution function value calculated using a normal approximation
57      * @throws MathException if an error occurs computing the normal approximation
58      */
59     public double normalApproximateProbability(int x) throws MathException;
60 }
Popular Tags