>>> import scipy.signal as sig
>>> b = [1, 1]
>>> a = [1, 1, 0.5]
>>> r, p, k = sig.residue(b,a)
>>> r
array([0.5-0.5j, 0.5+0.5j])

>>> p
array([-0.5+0.5j, -0.5-0.5j])

>>> k
array([0.])

>>> import harold as har
>>> G = Transfer([1, 1], [1, 1, 0.5], dt=1)
>>> impulse_response_plot(G);