Comment on “Description of FIR digital filters in the form of parallel connection of linear phase FIRs”

The original paper (see ibid., vol32, no. 11 p. 979-80, 1996) showed that an Nth-order one-dimensional digital FIR filter may be represented as a parallel connection of [log₂(N + 2)] linear phase digital FIR filters. Iwaki and Ishii state that their linear phase decomposition is not unique and that several decompositions are possible. The authors also state that linear phase decompositions may be useful in decomposing a general filter design problem into several linear phase subproblems, so that well-developed linear phase filter design techniques could be applied to a general filter design problem. The linear phase decomposition given in this comment is based on a given theorem