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- /*
- * Copyright (C) 2019, Matthias Sohn <matthias.sohn@sap.com>
- * and other copyright owners as documented in the project's IP log.
- *
- * This program and the accompanying materials are made available
- * under the terms of the Eclipse Distribution License v1.0 which
- * accompanies this distribution, is reproduced below, and is
- * available at http://www.eclipse.org/org/documents/edl-v10.php
- *
- * All rights reserved.
- *
- * Redistribution and use in source and binary forms, with or
- * without modification, are permitted provided that the following
- * conditions are met:
- *
- * - Redistributions of source code must retain the above copyright
- * notice, this list of conditions and the following disclaimer.
- *
- * - Redistributions in binary form must reproduce the above
- * copyright notice, this list of conditions and the following
- * disclaimer in the documentation and/or other materials provided
- * with the distribution.
- *
- * - Neither the name of the Eclipse Foundation, Inc. nor the
- * names of its contributors may be used to endorse or promote
- * products derived from this software without specific prior
- * written permission.
- *
- * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND
- * CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES,
- * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
- * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
- * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
- * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
- * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
- * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
- * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
- * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
- * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
- * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
- * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
- */
- package org.eclipse.jgit.util;
-
- /**
- * Simple double statistics, computed incrementally, variance and standard
- * deviation using Welford's online algorithm, see
- * https://en.wikipedia.org/wiki/Algorithms_for_calculating_variance#Welford's_online_algorithm
- *
- * @since 5.1.9
- */
- public class Stats {
- private int n = 0;
-
- private double avg = 0.0;
-
- private double min = 0.0;
-
- private double max = 0.0;
-
- private double sum = 0.0;
-
- /**
- * Add a value
- *
- * @param x
- * value
- */
- public void add(double x) {
- n++;
- min = n == 1 ? x : Math.min(min, x);
- max = n == 1 ? x : Math.max(max, x);
- double d = x - avg;
- avg += d / n;
- sum += d * d * (n - 1) / n;
- }
-
- /**
- * @return number of the added values
- */
- public int count() {
- return n;
- }
-
- /**
- * @return minimum of the added values
- */
- public double min() {
- if (n < 1) {
- return Double.NaN;
- }
- return min;
- }
-
- /**
- * @return maximum of the added values
- */
- public double max() {
- if (n < 1) {
- return Double.NaN;
- }
- return max;
- }
-
- /**
- * @return average of the added values
- */
-
- public double avg() {
- if (n < 1) {
- return Double.NaN;
- }
- return avg;
- }
-
- /**
- * @return variance of the added values
- */
- public double var() {
- if (n < 2) {
- return Double.NaN;
- }
- return sum / (n - 1);
- }
-
- /**
- * @return standard deviation of the added values
- */
- public double stddev() {
- return Math.sqrt(this.var());
- }
- }
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