คุณสมบัติของโปรแกรม · มุมที่จุดศูนย์กลางทรงกลมหน่วย

from math import asin, cos, isfinite, radians, sin, sqrt
def central_angle(lat1, lon1, lat2, lon2):
    values = (lat1, lon1, lat2, lon2)
    if any(type(x) not in (int, float) or not -limit <= x <= limit
           or not isfinite(x) for x, limit in zip(values, (90, 180, 90, 180))):
        raise ValueError("bounded finite coordinates")
    p, q = radians(lat1), radians(lat2)
    a = sin((q-p)/2)**2 + cos(p)*cos(q)*sin(radians(lon2-lon1)/2)**2
    return 2 * asin(sqrt(min(1.0, max(0.0, a))))