def _rhumb3(self, other):
'''(INTERNAL) Rhumb_ helper function.
@param other: The other point (spherical C{LatLon}).
'''
self.others(other)
a1, b1 = self.to2ab()
a2, b2 = other.to2ab()
# if |db| > 180 take shorter rhumb
# line across the anti-meridian
db = wrapPI(b2 - b1)
dp = log(tanPI_2_2(a2) / tanPI_2_2(a1))
return (a2 - a1), db, dp
def _xb(a1, b1, end, a, b, wrap):
# difference between the bearing to (a, b) and the given
# bearing is negative if both are in opposite directions
r = bearing_(a1, b1, radians(a), radians(b), wrap=wrap)
return PI_2 - abs(wrapPI(r - radians(end)))