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1   /*
2    * Copyright 2003-2004 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  
19  /**
20   * Base interface for discrete distributions.
21   *
22   * @version $Revision: 155427 $ $Date: 2005-02-26 06:11:52 -0700 (Sat, 26 Feb 2005) $
23   */
24  public interface DiscreteDistribution extends Distribution {
25      /**
26       * For a random variable X whose values are distributed according
27       * to this distribution, this method returns P(X = x). In other words, this
28       * method represents the probability mass function, or PMF for the distribution.
29       * 
30       * @param x the value at which the probability mass function is evaluated.
31       * @return the value of the probability mass function at x
32       */
33      double probability(double x);
34  }