def test_commutes_tolerance():
atol = 0.5
x = np.array([[0, 1], [1, 0]])
z = np.array([[1, 0], [0, -1]])
# Pays attention to specified tolerance.
assert matrix_commutes(x, x + z * 0.1, atol=atol)
assert not matrix_commutes(x, x + z * 0.5, atol=atol)
def _strat_commutes_from_matrix(
v1: Any, v2: Any, *,
atol: float) -> Union[bool, NotImplementedType, None]:
"""Attempts to determine commutativity of matrices."""
if not isinstance(v1, np.ndarray) or not isinstance(v2, np.ndarray):
return NotImplemented
if v1.shape != v2.shape:
return None
return linalg.matrix_commutes(v1, v2, atol=atol)
def test_commutes():
assert matrix_commutes(np.empty((0, 0)), np.empty((0, 0)))
assert not matrix_commutes(np.empty((1, 0)), np.empty((0, 1)))
assert not matrix_commutes(np.empty((0, 1)), np.empty((1, 0)))
assert not matrix_commutes(np.empty((1, 0)), np.empty((1, 0)))
assert not matrix_commutes(np.empty((0, 1)), np.empty((0, 1)))
assert matrix_commutes(np.array([[1]]), np.array([[2]]))
assert matrix_commutes(np.array([[1]]), np.array([[0]]))
x = np.array([[0, 1], [1, 0]])
y = np.array([[0, -1j], [1j, 0]])
z = np.array([[1, 0], [0, -1]])
xx = np.kron(x, x)
zz = np.kron(z, z)
assert matrix_commutes(x, x)
assert matrix_commutes(y, y)
assert matrix_commutes(z, z)
assert not matrix_commutes(x, y)
assert not matrix_commutes(x, z)
assert not matrix_commutes(y, z)
assert matrix_commutes(xx, zz)
assert matrix_commutes(xx, np.diag([1, -1, -1, 1 + 1e-9]))
