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Java example source code file (SumOfSquares.java)

This example Java source code file (SumOfSquares.java) is included in the alvinalexander.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" TM.

Learn more about this Java project at its project page.

Java - Java tags/keywords

abstractstorelessunivariatestatistic, mathillegalargumentexception, nullargumentexception, override, serializable, sumofsquares

The SumOfSquares.java Java example source code

/*
 * 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.MathUtils;

/**
 * Returns the sum of the squares of the available values.
 * <p>
 * If there are no values in the dataset, then 0 is returned.
 * If any of the values are
 * <code>NaN, then NaN is returned.

* <p> * <strong>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 <code>increment() or * <code>clear() method, it must be synchronized externally.

* */ public class SumOfSquares extends AbstractStorelessUnivariateStatistic implements Serializable { /** Serializable version identifier */ private static final long serialVersionUID = 1460986908574398008L; /** */ private long n; /** * The currently running sumSq */ private double value; /** * Create a SumOfSquares instance */ public SumOfSquares() { n = 0; value = 0; } /** * Copy constructor, creates a new {@code SumOfSquares} identical * to the {@code original} * * @param original the {@code SumOfSquares} instance to copy * @throws NullArgumentException if original is null */ public SumOfSquares(SumOfSquares original) throws NullArgumentException { copy(original, this); } /** * {@inheritDoc} */ @Override public void increment(final double d) { value += d * d; n++; } /** * {@inheritDoc} */ @Override public double getResult() { return value; } /** * {@inheritDoc} */ public long getN() { return n; } /** * {@inheritDoc} */ @Override public void clear() { value = 0; n = 0; } /** * Returns the sum of the squares of the entries in the specified portion of * the input array, or <code>Double.NaN if the designated subarray * is empty. * <p> * Throws <code>MathIllegalArgumentException if the array is null.

* * @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 squares 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 sumSq = Double.NaN; if (test(values, begin, length, true)) { sumSq = 0.0; for (int i = begin; i < begin + length; i++) { sumSq += values[i] * values[i]; } } return sumSq; } /** * {@inheritDoc} */ @Override public SumOfSquares copy() { SumOfSquares result = new SumOfSquares(); // no try-catch or advertised exception here because args are valid copy(this, result); return result; } /** * Copies source to dest. * <p>Neither source nor dest can be null.

* * @param source SumOfSquares to copy * @param dest SumOfSquares to copy to * @throws NullArgumentException if either source or dest is null */ public static void copy(SumOfSquares source, SumOfSquares dest) throws NullArgumentException { MathUtils.checkNotNull(source); MathUtils.checkNotNull(dest); dest.setData(source.getDataRef()); dest.n = source.n; dest.value = source.value; } }

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