| Distance.java |
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 }