def test_cross_non_numeric(self):
u = ('a', 'b', 'c')
v = (1, 1, 0)
with self.assertRaises(
TypeError,
msg='should raise TypeError when passing non-3d vectors'):
cross(u, v)
def test_cross_non_3d(self):
u = (1, 0)
v = (1, 1, 0)
with self.assertRaises(
ValueError,
msg='should raise TypeError when passing non-3d vectors'):
cross(u, v)
def test_cross_happy_path(self):
u = (1, 2, 3)
v = (4, 5, 6)
cross_actual_result = cross(u, v)
cross_expected_result = (12 - 15, -6 + 12, 5 - 8
) # using determinant matrix
self.assertEqual(cross_actual_result,
cross_expected_result,
msg='cross should match')
def plane_equation(p0, p1, p2):
"""Returns the coefficients a, b, c, d for a plane's equation in
its standard form (ax + by + cz = d) given three points p0, p1, p2
in the plane
"""
vector_in_the_plane_1 = subtract(p1, p0)
vector_in_the_plane_2 = subtract(p2, p0)
vector_perpendicular_to_the_plane = cross(vector_in_the_plane_1,
vector_in_the_plane_2)
a, b, c = vector_perpendicular_to_the_plane
d = dot(vector_perpendicular_to_the_plane, p1)
return a, b, c, d