/*

  * 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.giraph.utils;

 import org.apache.hadoop.io.DoubleWritable;

 import java.util.Iterator;

 /**

  * A helper class for math related operations with writables

  */

 public class MathUtils {

   /**

    * Utility classes cannot be instantiated

    */

   private MathUtils() {

   }

   /**

    * Sums up a sequence of double values

    * @param values double values

    * @return sum of double values

    */

   public static double sum(Iterable<DoubleWritable> values) {

     return sum(values.iterator());

   }

   /**

    * Sums up a sequence of double values

    * @param values double values

    * @return sum of double values

    */

   public static double sum(Iterator<DoubleWritable> values) {

     double sum = 0;

     while (values.hasNext()) {

       sum += values.next().get();

     }

     return sum;

   }

 }