001    /*
002     * Licensed to the Apache Software Foundation (ASF) under one or more
003     * contributor license agreements.  See the NOTICE file distributed with
004     * this work for additional information regarding copyright ownership.
005     * The ASF licenses this file to You under the Apache License, Version 2.0
006     * (the "License"); you may not use this file except in compliance with
007     * the License.  You may obtain a copy of the License at
008     *
009     *      http://www.apache.org/licenses/LICENSE-2.0
010     *
011     * Unless required by applicable law or agreed to in writing, software
012     * distributed under the License is distributed on an "AS IS" BASIS,
013     * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014     * See the License for the specific language governing permissions and
015     * limitations under the License.
016     */
017    package org.apache.commons.math.stat.descriptive;
018    
019    
020    /**
021     * Base interface implemented by all statistics.
022     * 
023     * @version $Revision: 780541 $ $Date: 2009-05-31 20:47:02 -0400 (Sun, 31 May 2009) $
024     */
025    public interface UnivariateStatistic {
026    
027        /**
028         * Returns the result of evaluating the statistic over the input array.
029         * 
030         * @param values input array
031         * @return the value of the statistic applied to the input array
032         */
033        double evaluate(double[] values);
034    
035        /**
036         * Returns the result of evaluating the statistic over the specified entries
037         * in the input array.
038         * 
039         * @param values the input array
040         * @param begin the index of the first element to include
041         * @param length the number of elements to include
042         * @return the value of the statistic applied to the included array entries
043         */
044        double evaluate(double[] values, int begin, int length);
045        
046        /**
047         * Returns a copy of the statistic with the same internal state.
048         * 
049         * @return a copy of the statistic
050         */
051        UnivariateStatistic copy();
052    
053    }