/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.apache.commons.math.stat.descriptive;

/**
 * Base interface implemented by all statistics.
 * 
 * @version $Revision$ $Date$
 */
public interface UnivariateStatistic {

	/**
	 * Returns the result of evaluating the statistic over the input array.
	 * 
	 * @param values
	 *            input array
	 * @return the value of the statistic applied to the input array
	 */
	double evaluate(double[] values);

	/**
	 * Returns the result of evaluating the statistic over the specified entries
	 * in the input array.
	 * 
	 * @param values
	 *            the input array
	 * @param begin
	 *            the index of the first element to include
	 * @param length
	 *            the number of elements to include
	 * @return the value of the statistic applied to the included array entries
	 */
	double evaluate(double[] values, int begin, int length);

	/**
	 * Returns a copy of the statistic with the same internal state.
	 * 
	 * @return a copy of the statistic
	 */
	UnivariateStatistic copy();

}
