Distance.java

package com.njtransit.utils;

public class Distance {

	private static final int R = 6371000;
	
	/**
	 * 
	 * @param lat1
	 * @param lon1
	 * @param lat2
	 * @param lon2
	 * @return distance between points in meters
	 */
	public static double greatCircle(double lat1, double lon1, double lat2, double lon2) {
		double dLat = Math.toRadians(lat2-lat1);
		double dLon = Math.toRadians(lon2-lon1);
		double a = Math.sin(dLat/2) * Math.sin(dLat/2) + Math.cos(Math.toRadians(lat1)) * Math.cos(Math.toRadians(lat2)) * Math.sin(dLon/2) * Math.sin(dLon/2);
		double c = 2 * Math.atan2(Math.sqrt(a), Math.sqrt(1-a));
		return R * c;
	}	
}