def test_independent_no_graph_mode(self):
"""In non-graph mode, it is impossible to determine
if a parameter is independent or not"""
with qml.tape.JacobianTape() as tape:
qml.RX(0.543, wires=[0])
qml.RY(-0.654, wires=[1])
qml.expval(qml.PauliY(0))
_gradient_analysis(tape, use_graph=False)
assert tape._par_info[0]["grad_method"] == "A"
assert tape._par_info[1]["grad_method"] == "A"
def test_independent(self):
"""Test that an independent variable is properly marked
as having a zero gradient"""
with qml.tape.JacobianTape() as tape:
qml.RX(0.543, wires=[0])
qml.RY(-0.654, wires=[1])
qml.expval(qml.PauliY(0))
_gradient_analysis(tape)
assert tape._par_info[0]["grad_method"] == "A"
assert tape._par_info[1]["grad_method"] == "0"
def test_non_differentiable(self):
"""Test that a non-differentiable parameter is
correctly marked"""
psi = np.array([1, 0, 1, 0]) / np.sqrt(2)
with qml.tape.JacobianTape() as tape:
qml.QubitStateVector(psi, wires=[0, 1])
qml.RX(0.543, wires=[0])
qml.RY(-0.654, wires=[1])
qml.CNOT(wires=[0, 1])
qml.probs(wires=[0, 1])
_gradient_analysis(tape)
assert tape._par_info[0]["grad_method"] is None
assert tape._par_info[1]["grad_method"] == "A"
assert tape._par_info[2]["grad_method"] == "A"
def test_finite_diff(self, monkeypatch):
"""If an op has grad_method=F, this should be respected"""
monkeypatch.setattr(qml.RX, "grad_method", "F")
psi = np.array([1, 0, 1, 0]) / np.sqrt(2)
with qml.tape.JacobianTape() as tape:
qml.QubitStateVector(psi, wires=[0, 1])
qml.RX(0.543, wires=[0])
qml.RY(-0.654, wires=[1])
qml.CNOT(wires=[0, 1])
qml.probs(wires=[0, 1])
_gradient_analysis(tape)
assert tape._par_info[0]["grad_method"] is None
assert tape._par_info[1]["grad_method"] == "F"
assert tape._par_info[2]["grad_method"] == "A"
def test_analysis_caching(self, mocker):
"""Test that the gradient analysis is only executed once per tape"""
psi = np.array([1, 0, 1, 0]) / np.sqrt(2)
with qml.tape.JacobianTape() as tape:
qml.QubitStateVector(psi, wires=[0, 1])
qml.RX(0.543, wires=[0])
qml.RY(-0.654, wires=[1])
qml.CNOT(wires=[0, 1])
qml.probs(wires=[0, 1])
spy = mocker.spy(tape, "_grad_method")
_gradient_analysis(tape)
spy.assert_called()
assert tape._par_info[0]["grad_method"] is None
assert tape._par_info[1]["grad_method"] == "A"
assert tape._par_info[2]["grad_method"] == "A"
spy = mocker.spy(tape, "_grad_method")
_gradient_analysis(tape)
spy.assert_not_called()