def test_chop_all(self):
"""Test that chop returns an identity operator with coeff 0 if all coeffs are chopped."""
eps = 1e-10
op = SparsePauliOp(["X", "Z"], coeffs=[eps, eps])
simplified = op.chop(tol=eps)
expected = SparsePauliOp(["I"], coeffs=[0.0])
self.assertEqual(simplified, expected)
def test_chop(self):
"""Test chop, which individually truncates real and imaginary parts of the coeffs."""
eps = 1e-10
op = SparsePauliOp(
["XYZ", "ZII", "ZII", "YZY"],
coeffs=[eps + 1j * eps, 1 + 1j * eps, eps + 1j, 1 + 1j])
simplified = op.chop(tol=eps)
expected_coeffs = [1, 1j, 1 + 1j]
expected_paulis = ["ZII", "ZII", "YZY"]
self.assertListEqual(simplified.coeffs.tolist(), expected_coeffs)
self.assertListEqual(simplified.paulis.to_labels(), expected_paulis)
