Navigation.py 文件源码

def loxodrome(latA, lonA, latB, lonB):  # lossodromica
    # Rhumb line navigation
    # Takes two points on earth and returns:
    # the distance and constant (true) bearing one would need to
    # follow to reach it.
    # Doesn't function near poles:
    # but you shouldn't be sailing near the poles anyways!
    # when latB = -90: math domain error log(0)
    # when latA = -90 [zero divison error]
    # when A==B returns (0.0,0.0)
    # if latA == latB:
    if math.copysign(latA-latB, 1) <= math.radians(0.1/3600.0):
        q = math.cos(latA)
    else:
        Df = math.log(math.tan(latB/2+math.pi/4)
                      / math.tan(latA/2+math.pi/4), math.e)
        q = (latB-latA) * 1.0/Df
    Distance = EARTH_RADIUS * ((latA-latB)**2+(q*(lonA-lonB))**2)**0.5
    Heading = math.atan2(-q*(lonB-lonA), (latB-latA))
    if Heading < 0:
        Heading = Heading + 2.0 * math.pi  # atan2:[-pi,pi]
    return Distance, Heading