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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.stat.descriptive;
17  
18  /**
19   *  Reporting interface for basic univariate statistics.
20   *
21    * @version $Revision: 155427 $ $Date: 2005-02-26 06:11:52 -0700 (Sat, 26 Feb 2005) $
22   */
23  public interface StatisticalSummary {
24      /** 
25       * Returns the <a href="http://www.xycoon.com/arithmetic_mean.htm">
26       * arithmetic mean </a> of the available values 
27       * @return The mean or Double.NaN if no values have been added.
28       */
29      public abstract double getMean();
30      /** 
31       * Returns the variance of the available values.
32       * @return The variance, Double.NaN if no values have been added 
33       * or 0.0 for a single value set.  
34       */
35      public abstract double getVariance();
36      /** 
37       * Returns the standard deviation of the available values.
38       * @return The standard deviation, Double.NaN if no values have been added 
39       * or 0.0 for a single value set. 
40       */
41      public abstract double getStandardDeviation();
42      /** 
43       * Returns the maximum of the available values
44       * @return The max or Double.NaN if no values have been added.
45       */
46      public abstract double getMax();
47      /** 
48      * Returns the minimum of the available values
49      * @return The min or Double.NaN if no values have been added.
50      */
51      public abstract double getMin();
52      /** 
53       * Returns the number of available values
54       * @return The number of available values
55       */
56      public abstract long getN();
57      /**
58       * Returns the sum of the values that have been added to Univariate.
59       * @return The sum or Double.NaN if no values have been added
60       */
61      public abstract double getSum();
62  }