/* * 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.summary; import java.io.Serializable; import org.apache.commons.math.stat.descriptive.AbstractStorelessUnivariateStatistic; import org.apache.commons.math.stat.descriptive.WeightedEvaluation; import org.apache.commons.math.util.FastMath; /** * Returns the product of the available values. *
* If there are no values in the dataset, or any of the values are
* NaN
, then NaN
is returned.
* Note that this implementation is not synchronized. If
* multiple threads access an instance of this class concurrently, and at least
* one of the threads invokes the increment()
or
* clear()
method, it must be synchronized externally.
Double.NaN
if the designated subarray
* is empty.
*
* Throws IllegalArgumentException
if the array is null.
Returns the weighted product of the entries in the specified portion of
* the input array, or Double.NaN
if the designated subarray
* is empty.
Throws IllegalArgumentException
if any of the following are true:
*
Uses the formula,
* weighted product = ∏values[i]weights[i] ** that is, the weights are applied as exponents when computing the weighted product. * * @param values the input array * @param weights the weights array * @param begin index of the first array element to include * @param length the number of elements to include * @return the product of the values or Double.NaN if length = 0 * @throws IllegalArgumentException if the parameters are not valid * @since 2.1 */ public double evaluate(final double[] values, final double[] weights, final int begin, final int length) { double product = Double.NaN; if (test(values, weights, begin, length)) { product = 1.0; for (int i = begin; i < begin + length; i++) { product *= FastMath.pow(values[i], weights[i]); } } return product; } /** *
Returns the weighted product of the entries in the input array.
* *Throws IllegalArgumentException
if any of the following are true:
*
Uses the formula,
* weighted product = ∏values[i]weights[i] ** that is, the weights are applied as exponents when computing the weighted product. * * @param values the input array * @param weights the weights array * @return the product of the values or Double.NaN if length = 0 * @throws IllegalArgumentException if the parameters are not valid * @since 2.1 */ public double evaluate(final double[] values, final double[] weights) { return evaluate(values, weights, 0, values.length); } /** * {@inheritDoc} */ @Override public Product copy() { Product result = new Product(); copy(this, result); return result; } /** * Copies source to dest. *
Neither source nor dest can be null.
* * @param source Product to copy * @param dest Product to copy to * @throws NullPointerException if either source or dest is null */ public static void copy(Product source, Product dest) { dest.setData(source.getDataRef()); dest.n = source.n; dest.value = source.value; } }