On the synthesis of 2-D state-space digital filters with minimum roundoff noise

Some results reported recently by T. Hinamoto, T. Hamanaka, and S. Maekawa (see ibid., vol.CAS-35, no.8, p.1037-42, 1988) concerning two-dimensional state-space digital filters with minimum roundoff noise are discussed. It is shown that the Roesser realization used in this work is suboptimal, and that another Roesser realization can be obtained that has approximately the same roundoff noise as the corresponding Fornasini-Marchesini realization. In effect, the claim made about the possible reduction of roundoff noise by using the method of T. Hinamoto et al. remains unsubstantiated.<
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