It is shown that reduced order models produced by the least-squares Padé method for discrete-time systems can sometimes produce misleading results for step and polynomial inputs. A more representative way of deriving such models is put forward and a numerical example is given to illustrate the points raised in the discussion.
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LucasT. N.Constrained optimal Padé model reduction. Trans. ASME, J. Dynamic Systems, Measmt, Control, 1997, 119, 685–690.
