An adaptive IIR algorithm with unimodal performance surfaces

The authors develop an adaptive IIR (infinite-impulse response) algorithm by means of least squares inverses; the algorithm also guarantees the resulting IIR system to be stable. This IIR algorithm consists of two subalgorithms, i.e. the all-pole Q_N( z) and all-zero P_N(z) algorithms. Both are with quadratic performance surfaces and stable. The iterations for Q_N(z) and P_N(z ) can be executed simultaneously or alternatively. The all-pole part is independent of P_N(z), but the all-zero part depends on Q_N(z) at each iteration. In many cases, the all-pole model itself is a fairly good approximation of an IIR system