latlng_dist

def latlng_dist(src_lat, src_lng, dest_lat, dest_lng):
    if src_lat == dest_lat and src_lng == dest_lng:
        return 0.0
    theta = float(src_lng) - float(dest_lng);
    src_lat_radians = math.radians(float(src_lat));
    dest_lat_radians = math.radians(float(dest_lat));
    dist = math.sin(src_lat_radians) * math.sin(dest_lat_radians) + \
        math.cos(src_lat_radians) * math.cos(dest_lat_radians) * \
        math.cos(math.radians(theta));
    dist = math.acos(dist);
    dist = math.degrees(dist);
    dist *= (60.0 * 1.1515 * 1.609344 * 1000.0);
    return dist;