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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.math3.stat.descriptive;
18  
19  import org.apache.commons.math3.exception.MathIllegalArgumentException;
20  import org.apache.commons.math3.util.MathArrays;
21  
22  
23  /**
24   * Base interface implemented by all statistics.
25   *
26   */
27  public interface UnivariateStatistic extends MathArrays.Function {
28      /**
29       * Returns the result of evaluating the statistic over the input array.
30       *
31       * @param values input array
32       * @return the value of the statistic applied to the input array
33       * @throws MathIllegalArgumentException  if values is null
34       */
35      double evaluate(double[] values) throws MathIllegalArgumentException;
36  
37      /**
38       * Returns the result of evaluating the statistic over the specified entries
39       * in the input array.
40       *
41       * @param values the input array
42       * @param begin the index of the first element to include
43       * @param length the number of elements to include
44       * @return the value of the statistic applied to the included array entries
45       * @throws MathIllegalArgumentException if values is null or the indices are invalid
46       */
47      double evaluate(double[] values, int begin, int length) throws MathIllegalArgumentException;
48  
49      /**
50       * Returns a copy of the statistic with the same internal state.
51       *
52       * @return a copy of the statistic
53       */
54      UnivariateStatistic copy();
55  }