Unimodularity of Zeros of Self-inversive Polynomials
نویسندگان
چکیده
We generalise a necessary and sufficient condition given by Cohn for all the zeros of a self-inversive polynomial to be on the unit circle. Our theorem implies some sufficient conditions found by Lakatos, Losonczi and Schinzel. We apply our result to the study of a polynomial family closely related to Ramanujan polynomials, recently introduced by Gun, Murty and Rath, and studied by Murty, Smyth and Wang as well as by Laĺın and Rogers. We prove that all polynomials in this family have their zeros on the unit circle, a result conjectured by Laĺın and Rogers on computational evidence.
منابع مشابه
On the Zeros of Self-Inversive Polynomials
A classical result due to Cohn states that a self-inversive polynomial has all its zeros on the unit circle if and only if all the zeros of its derivative lie in the closed unit disk. A more flexible necessary and sufficient condition than that of Cohn’s was given by Chen. However those results do not give any information on the simplicity of zeros of a self-inversive polynomial. This paper mod...
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