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1   /*
2    * Licensed to the Apache Software Foundation (ASF) under one or more
3    * contributor license agreements.  See the NOTICE file distributed with
4    * this work for additional information regarding copyright ownership.
5    * The ASF licenses this file to You under the Apache License, Version 2.0
6    * (the "License"); you may not use this file except in compliance with
7    * the License.  You may obtain a copy of the License at
8    *
9    *      http://www.apache.org/licenses/LICENSE-2.0
10   *
11   * Unless required by applicable law or agreed to in writing, software
12   * distributed under the License is distributed on an "AS IS" BASIS,
13   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14   * See the License for the specific language governing permissions and
15   * limitations under the License.
16   */
17  package org.apache.commons.math.stat.descriptive;
18  
19  /**
20   *  Reporting interface for basic univariate statistics.
21   *
22    * @version $Revision: 670469 $ $Date: 2008-06-23 04:01:38 -0400 (Mon, 23 Jun 2008) $
23   */
24  public interface StatisticalSummary {
25      /** 
26       * Returns the <a href="http://www.xycoon.com/arithmetic_mean.htm">
27       * arithmetic mean </a> of the available values 
28       * @return The mean or Double.NaN if no values have been added.
29       */
30      public abstract double getMean();
31      /** 
32       * Returns the variance of the available values.
33       * @return The variance, Double.NaN if no values have been added 
34       * or 0.0 for a single value set.  
35       */
36      public abstract double getVariance();
37      /** 
38       * Returns the standard deviation of the available values.
39       * @return The standard deviation, Double.NaN if no values have been added 
40       * or 0.0 for a single value set. 
41       */
42      public abstract double getStandardDeviation();
43      /** 
44       * Returns the maximum of the available values
45       * @return The max or Double.NaN if no values have been added.
46       */
47      public abstract double getMax();
48      /** 
49      * Returns the minimum of the available values
50      * @return The min or Double.NaN if no values have been added.
51      */
52      public abstract double getMin();
53      /** 
54       * Returns the number of available values
55       * @return The number of available values
56       */
57      public abstract long getN();
58      /**
59       * Returns the sum of the values that have been added to Univariate.
60       * @return The sum or Double.NaN if no values have been added
61       */
62      public abstract double getSum();
63  }