1   /**
2    * Copyright (c) 2000-2010 Liferay, Inc. All rights reserved.
3    *
4    * This library is free software; you can redistribute it and/or modify it under
5    * the terms of the GNU Lesser General Public License as published by the Free
6    * Software Foundation; either version 2.1 of the License, or (at your option)
7    * any later version.
8    *
9    * This library is distributed in the hope that it will be useful, but WITHOUT
10   * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
11   * FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for more
12   * details.
13   */
14  
15  package com.liferay.util;
16  
17  /**
18   * <a href="Distance.java.html"><b><i>View Source</i></b></a>
19   *
20   * @author Brian Wing Shun Chan
21   */
22  public class Distance {
23  
24      public static double calculate(double lat1, double lon1,
25                                     double lat2, double lon2) {
26  
27          // Convert from radians to degrees
28  
29          lat1 = (Math.PI * lat1) / 180;
30          lon1 = (Math.PI * lon1) / 180;
31          lat2 = (Math.PI * lat2) / 180;
32          lon2 = (Math.PI * lon2) / 180;
33  
34          double miles =
35              3963.4 *
36              Math.acos(
37                  (Math.sin(lat1) * Math.sin(lat2)) +
38                  (Math.cos(lat1) * Math.cos(lat2) * Math.cos(lon1 - lon2)));
39  
40          return miles;
41      }
42  
43      public static double kmToMiles(double km) {
44          return km * 0.621;
45      }
46  
47      public static double milesToKm(double miles) {
48          return miles / 0.621;
49      }
50  
51  }