def test_angle_between_directions(self):
d111 = HklDirection(1, 1, 1)
d110 = HklDirection(1, 1, 0)
d100 = HklDirection(1, 0, 0)
dm111 = HklDirection(-1, 1, 1)
self.assertAlmostEqual(
d100.angle_with_direction(d110) * 180 / np.pi, 45.0)
self.assertAlmostEqual(
d111.angle_with_direction(d110) * 180 / np.pi, 35.26, 2)
self.assertAlmostEqual(
d111.angle_with_direction(dm111) * 180 / np.pi, 70.528, 2)
def test_angle_with_directions(self):
(a, b, c) = (1.022, 0.596, 0.481)
olivine = Lattice.orthorhombic(a, b, c)
(h1, k1, l1) = (1., 1., 1.)
(h2, k2, l2) = (3., 3., 2.)
d1 = HklDirection(h1, k1, l1, olivine)
d2 = HklDirection(h2, k2, l2, olivine)
# compare with formula in orthorhombic lattice, angle must be 6.589 degrees
angle = np.arccos(
((h1 * h2 * a**2) + (k1 * k2 * b**2) + (l1 * l2 * c**2)) /
(np.sqrt(a**2 * h1**2 + b**2 * k1**2 + c**2 * l1**2) *
np.sqrt(a**2 * h2**2 + b**2 * k2**2 + c**2 * l2**2)))
self.assertAlmostEqual(d1.angle_with_direction(d2), angle)