Figure 6.3 illustrates the use of residuez (§H.5)
for performing a partial fraction expansion on the transfer function
The complex-conjugate terms can be combined to obtain two real
second-order sections, giving a total of one real first-order section
in parallel with two real second-order sections, as discussed and
depicted in §3.11.
Use of residuez to perform
a partial fraction expansion of an IIR filter transfer function