def distance(self, p1, p2):
'''Return the L{flatPolar_} distance in C{radians}.
'''
r, _ = unrollPI(p1.lam, p2.lam, wrap=self._wrap)
return flatPolar_(p2.phi, p1.phi, r)
def _distances(self, x, y): # (x, y) radians
for xk, yk in zip(self._xs, self._ys):
d, _ = unrollPI(xk, x, wrap=self._wrap)
yield flatPolar_(yk, y, d) # radians