Further comments on "Elimination of singular cases in Jurys test"
Mohamed M. Bayoumi, Kwok Swan Wong · IEEE Transactions on Automatic Control · 1981
In recent papers [1] and [2], the authors tried to modify the earlier development [3] of Jury's table [4] to eliminate singular cases. But the method of expanding and contracting the unit circle infinitesimally in [2] does not handle all singular cases. This is illustrated by examples. The remainder of this correspondence shows the general way of expanding and contracting the unit circle. The exact radii of the expanded and contracted circles are also given so that more information about the roots can be obtained. This is also illustrated by examples.