1 /* 2 * Licensed to the Apache Software Foundation (ASF) under one 3 * or more contributor license agreements. See the NOTICE file 4 * distributed with this work for additional information 5 * regarding copyright ownership. The ASF licenses this file 6 * to you under the Apache License, Version 2.0 (the 7 * "License"); you may not use this file except in compliance 8 * with the License. You may obtain a copy of the License at 9 * 10 * http://www.apache.org/licenses/LICENSE-2.0 11 * 12 * Unless required by applicable law or agreed to in writing, software 13 * distributed under the License is distributed on an "AS IS" BASIS, 14 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 15 * See the License for the specific language governing permissions and 16 * limitations under the License. 17 */ 18 19 package org.apache.giraph.utils; 20 21 import org.apache.hadoop.io.DoubleWritable; 22 23 import java.util.Iterator; 24 25 /** 26 * A helper class for math related operations with writables 27 */ 28 public class MathUtils { 29 30 /** 31 * Utility classes cannot be instantiated 32 */ 33 private MathUtils() { 34 } 35 36 /** 37 * Sums up a sequence of double values 38 * @param values double values 39 * @return sum of double values 40 */ 41 public static double sum(Iterable<DoubleWritable> values) { 42 return sum(values.iterator()); 43 } 44 45 /** 46 * Sums up a sequence of double values 47 * @param values double values 48 * @return sum of double values 49 */ 50 public static double sum(Iterator<DoubleWritable> values) { 51 double sum = 0; 52 while (values.hasNext()) { 53 sum += values.next().get(); 54 } 55 return sum; 56 } 57 }