/* * 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.math3.stat.descriptive.summary; import java.io.Serializable; import org.apache.commons.math3.exception.MathIllegalArgumentException; import org.apache.commons.math3.exception.NullArgumentException; import org.apache.commons.math3.stat.descriptive.AbstractStorelessUnivariateStatistic; import org.apache.commons.math3.util.FastMath; import org.apache.commons.math3.util.MathUtils; /** * Returns the sum of the natural logs for this collection of values. *
* Uses {@link org.apache.commons.math3.util.FastMath#log(double)} to compute the logs. * Therefore, *
NaN.
Double.POSITIVE_INFINITY
, but at least one value is 0, the
* result is Double.NEGATIVE_INFINITY.
Double.POSITIVE_INFINITY
and
* Double.NEGATIVE_INFINITY
are among the values, the result is
* NaN.
* 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 MathIllegalArgumentException
if the array is null.
* See {@link SumOfLogs}.
* * @param values the input array * @param begin index of the first array element to include * @param length the number of elements to include * @return the sum of the natural logs of the values or 0 if * length = 0 * @throws MathIllegalArgumentException if the array is null or the array index * parameters are not valid */ @Override public double evaluate(final double[] values, final int begin, final int length) throws MathIllegalArgumentException { double sumLog = Double.NaN; if (test(values, begin, length, true)) { sumLog = 0.0; for (int i = begin; i < begin + length; i++) { sumLog += FastMath.log(values[i]); } } return sumLog; } /** * {@inheritDoc} */ @Override public SumOfLogs copy() { SumOfLogs result = new SumOfLogs(); // No try-catch or advertised exception here because args are valid copy(this, result); return result; } /** * Copies source to dest. *Neither source nor dest can be null.
* * @param source SumOfLogs to copy * @param dest SumOfLogs to copy to * @throws NullArgumentException if either source or dest is null */ public static void copy(SumOfLogs source, SumOfLogs dest) throws NullArgumentException { MathUtils.checkNotNull(source); MathUtils.checkNotNull(dest); dest.setData(source.getDataRef()); dest.n = source.n; dest.value = source.value; } }