def METHOD_NAME(lat1, long1, lat2, long2):
    """
    http://www.johndcook.com/python_longitude_latitude.html
    Distance in miles multiply by 3960
    Distance in kilometers multiply by 6373
    """
    import math
    # Convert latitude and longitude to
    # spherical coordinates in radians.
    degrees_to_radians = math.pi/180.0
    # phi = 90 - latitude
    phi1 = (90.0 - lat1)*degrees_to_radians
    phi2 = (90.0 - lat2)*degrees_to_radians
    # theta = longitude
    theta1 = long1*degrees_to_radians
    theta2 = long2*degrees_to_radians
    # Compute spherical distance from spherical coordinates.
    # For two locations in spherical coordinates
    # (1, theta, phi) and (1, theta, phi)
    # cosine( arc length ) =
    #    sin phi sin phi' cos(theta-theta') + cos phi cos phi'
    # distance = rho * arc length
    cos = (math.sin(phi1)*math.sin(phi2)*math.cos(theta1 - theta2) +
           math.cos(phi1)*math.cos(phi2))
    arc = math.acos( cos )
    # Remember to multiply arc by the radius of the earth
    # in your favorite set of units to get length.
    return arc * 3960