var degreesPerRadian = 180.0 / Math.PI;
    var radiansPerDegree = Math.PI / 180.0;
    // Returns the bearing in degrees between two points.
    // North = 0, East = 90, South = 180, West = 270.
    function bearing(from, to) {
        // See T. Vincenty, Survey Review, 23, No 176, p 88-93,1975.
        // Convert to radians.
        var lat1 = from.latRadians();
        var lon1 = from.lngRadians();
        var lat2 = to.latRadians();
        var lon2 = to.lngRadians();
        // Compute the angle.
        var angle = -Math.atan2(Math.sin(lon1 - lon2) * Math.cos(lat2), Math.cos(lat1) * Math.sin(lat2) - Math.sin(lat1) * Math.cos(lat2) * Math.cos(lon1 - lon2));
        if (angle < 0.0) angle += Math.PI * 2.0;
        // And convert result to degrees.
        angle = angle * degreesPerRadian;
        angle = angle.toFixed(1);
        return angle;
    }