def get_angle(self, th_in, th_normal, rng, *args, **kwargs):
if rng is None:
rng = np.random
th_rel = vector.normalise_angle(th_in - th_normal)
antiparallels = np.isclose(np.abs(angle_dist(th_in, th_normal)), np.pi)
signs = np.where(antiparallels,
crandom.randbool(antiparallels.shape[0], rng),
np.sign(th_rel))
th_rel = signs * np.pi / 2.0
return th_normal + th_rel
def tumble(self, tumblers, rng=None):
if rng is None:
rng = np.random
self.sign[tumblers] = crandom.randbool(tumblers.sum(), rng=rng)