def test_identity(self, tol):
"""This test checks the rectangular decomposition for an identity unitary.
An identity unitary is decomposed via the rectangular decomposition of
Clements et al. and the resulting beamsplitters are multiplied together.
Test passes if the product matches identity.
"""
# TODO: this test currently uses the T and Ti functions used to compute
# Clements as the comparison. Probably should be changed.
n = 20
U = np.identity(n)
tlist, diags, _ = dec.triangular(U)
qrec = np.diag(diags)
for i in tlist:
qrec = dec.Ti(*i) @ qrec
assert np.allclose(U, qrec, atol=tol, rtol=0)
def test_unitary_validation(self):
"""Test that an exception is raised if not unitary"""
A = np.random.random([5, 5]) + 1j * np.random.random([5, 5])
with pytest.raises(ValueError, match="matrix is not unitary"):
dec.triangular(A)
