groups_have_uniform_coeffs

groups_have_uniform_coeffs(op, *, atol=1e-08, abs=True)

Returns, for each group, whether all of its coefficients are numerically equal.

With abs (the default), the coefficient magnitudes are compared, which is the assumption that group_coeff_means() makes when it averages abs(coeff). Without it, the coefficients must match exactly. Note that a Hermitian group may legitimately fail the stricter form, since a conjugate pair with complex coefficients has equal magnitudes but unequal coefficients. If the operator tracks no groups, this returns None.

An empty or single-term group is trivially uniform.

>>> from qiskit_fermions.operators import FermionOperator
>>> from qiskit_fermions.operators.terms.grouping import groups_have_uniform_coeffs
>>> op = FermionOperator.from_dict(
...     {
...         ((True, 0), (False, 1)): 1.0j,
...         ((True, 1), (False, 0)): -1.0j,
...     }
... )
>>> op.groups = [0, 0]
>>> groups_have_uniform_coeffs(op)  # equal magnitudes
[True]
>>> groups_have_uniform_coeffs(op, abs=False)  # but not equal coefficients
[False]

Parameters

• op – the operator whose groups to check.
• atol – The numerical accuracy upto which coefficients are considered equal. This value defaults to 1e-8.
• abs – Whether to compare coefficient magnitudes rather than the coefficients themselves. This value defaults to True.

Returns

One flag per group index, or None if the operator tracks no groups.

Raises

TypeError – if op is not a supported operator type (see OperatorTrait).