def test_map_to_fakenodes():
"""Test the fake nodes map in FakeNodesFactory."""
fac = FakeNodesFactory(UNIFORM_X)
test_argument = 1.0
assert np.isclose(
fac._map_to_fake_nodes([1.0], 2.0, test_argument), [1.0],
)
def test_fake_nodes_factory():
"""Test FakeNodesFactory in a specific regime in which the fake nodes
interpolation method works well.
"""
fac = FakeNodesFactory(UNIFORM_X)
assert not fac._opt_params
fac.run_classical(f_runge)
zne_value = fac.reduce()
assert np.isclose(zne_value, f_runge(0.0), atol=LARGE_TOL)
assert len(fac._opt_params) == len(UNIFORM_X)
assert np.isclose(fac._opt_params[-1], zne_value)
def test_fakenodes_scale_factors_equally_spaced():
"""FakeNodesFactory should only accept equally spaced scale factors."""
y_vals = [0.5, 1.0, 1.5]
with raises(
ValueError, match=r"The scale factors must be equally spaced."
):
_ = FakeNodesFactory(X_VALS).extrapolate(X_VALS, y_vals)
def test_fake_nodes_extrapolation():
"""Test that there exists a regime in which FakeNodesFactory
is better than RichardsonFactory.
Note: in many cases RichardsonFactory is better.
"""
y_vals = [f_runge(x) for x in UNIFORM_X]
zne_runge = FakeNodesFactory.extrapolate(UNIFORM_X, y_vals)
zne_richard = RichardsonFactory.extrapolate(UNIFORM_X, y_vals)
abs_err_runge = np.abs(zne_runge - f_runge(0.0))
abs_err_richard = np.abs(zne_richard - f_runge(0.0))
# Test Richardson extrapolation error is much larger
assert 500 * abs_err_runge < abs_err_richard
def test_fake_nodes_factory():
"""Test FakeNodesFactory in a specific regime in which the fake nodes
interpolation method works well.
"""
fac = FakeNodesFactory(UNIFORM_X)
assert not fac._opt_params
fac.run_classical(f_runge)
zne_value = fac.reduce()
assert np.isclose(zne_value, f_runge(0.0), atol=LARGE_TOL)
assert len(fac._opt_params) == len(UNIFORM_X)
assert np.isclose(fac._opt_params[-1], zne_value)
assert np.isclose(fac.extrapolate(UNIFORM_X, f_runge(UNIFORM_X)),
zne_value)
exp_vals = fac.get_expectation_values()
assert np.isclose(fac.extrapolate(UNIFORM_X, exp_vals), zne_value)
assert np.isclose(
fac.extrapolate(UNIFORM_X, exp_vals, full_output=True)[0],
zne_value,
)