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Set of Java utility classes, all completely independent, to provide lightweight solutions for common situations

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/*
 * Copyright (C) 2014 Zach Melamed
 * 
 * Latest version available online at https://github.com/zach-m/tectonica-commons
 *
 * Licensed 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 com.tectonica.util;

public class GeoUtils
{
	private static double EARTH_RADIUS = 6371; // kilometers

	public static double distanceKM(double lat1, double lng1, double lat2, double lng2)
	{
		double dLat = Math.toRadians(lat2 - lat1);
		double dLng = Math.toRadians(lng2 - lng1);
		double a = Math.sin(dLat / 2) * Math.sin(dLat / 2) + Math.cos(Math.toRadians(lat1)) * Math.cos(Math.toRadians(lat2))
				* Math.sin(dLng / 2) * Math.sin(dLng / 2);
		double c = 2 * Math.atan2(Math.sqrt(a), Math.sqrt(1 - a));
		return EARTH_RADIUS * c;
	}
}