def _compute_dA(system_size, theta):
    (u, v, cross_terms, same_terms) = _compute_vector_terms(system_size)
    return ((np.cos(theta) * cross_terms) - (np.sin(theta) * same_terms))
def _compute_dA(system_size, theta):
    (u, v, cross_terms, same_terms) = _compute_vector_terms(system_size)
    return ((np.cos(theta) * cross_terms) - (np.sin(theta) * same_terms))