Computes the bearing in degrees between two points on Earth. - Android Map

Android examples for Map:Location

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Description

Computes the bearing in degrees between two points on Earth.

Demo Code

/*******************************************************************************
 * Gaggle is Copyright 2010 by Geeksville Industries LLC, a California limited liability corporation. 
 * //from  w w  w  . j  ava  2  s  . c  om
 * Gaggle is distributed under a dual license.  We've chosen this approach because within Gaggle we've used a number
 * of components that Geeksville Industries LLC might reuse for commercial products.  Gaggle can be distributed under
 * either of the two licenses listed below.
 * 
 * This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; 
 * without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details. 
 * 
 * Commercial Distribution License
 * If you would like to distribute Gaggle (or portions thereof) under a license other than 
 * the "GNU General Public License, version 2", contact Geeksville Industries.  Geeksville Industries reserves
 * the right to release Gaggle source code under a commercial license of its choice.
 * 
 * GNU Public License, version 2
 * All other distribution of Gaggle must conform to the terms of the GNU Public License, version 2.  The full
 * text of this license is included in the Gaggle source, see assets/manual/gpl-2.0.txt.
 ******************************************************************************/
//package com.java2s;

public class Main {
    /**
     * Computes the bearing in degrees between two points on Earth.
     * 
     * @param lat1
     *            Latitude of the first point
     * @param lon1
     *            Longitude of the first point
     * @param lat2
     *            Latitude of the second point
     * @param lon2
     *            Longitude of the second point
     * @return Bearing between the two points in degrees. A value of 0 means due
     *         north.
     */
    public static double bearing(double lat1, double lon1, double lat2,
            double lon2) {
        double lat1Rad = Math.toRadians(lat1);
        double lat2Rad = Math.toRadians(lat2);
        double deltaLonRad = Math.toRadians(lon2 - lon1);

        double y = Math.sin(deltaLonRad) * Math.cos(lat2Rad);
        double x = Math.cos(lat1Rad) * Math.sin(lat2Rad)
                - Math.sin(lat1Rad) * Math.cos(lat2Rad)
                * Math.cos(deltaLonRad);
        return radToBearing(Math.atan2(y, x));
    }

    /**
     * Converts an angle in radians to degrees
     */
    public static double radToBearing(double rad) {
        return (Math.toDegrees(rad) + 360) % 360;
    }
}

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