Approximation of frequency response for sampled-data control systems

This paper proves that the frequency response gains of fast-sample/fast-hol d approximations of a sampled-data system converge to that of the original system as the sampling rate gets faster. While this may appear to hold triv ially, there is a serious technical difficulty, and the proof is indeed non trivial. It is also guaranteed that this convergence is uniform on the tota l frequency range. The latter property is necessary to guarantee that a sin gle approximant can be used for frequency response computation for the over all frequency range. (C) 1999 Elsevier Science Ltd. All rights reserved.