On damping ratio of polynomials with perturbed coefficients

C.B. Soh and C.S. Berger (1988) derived a sufficient condition for a family of interval polynomials to have a damping ratio of phi using Kharitonov's theorem for complex polynomials. This paper points out that the transformations used by Soh and Berger to obtain the sufficient conditions also guarantee a simplification of Kharitonov's theorem for complex polynomials. That is, the number of required polynomials to be Hurwitz is half the number specified by Soh and Berger.<
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