Zeros of Self-inversive Polynomials
نویسندگان
چکیده
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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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...
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The first author [1] proved that all zeros of the reciprocal polynomial Pm(z) = m ∑ k=0 Akz k (z ∈ C), of degree m ≥ 2 with real coefficients Ak ∈ R (i.e. Am 6= 0 and Ak = Am−k for all k = 0, . . . , [ m 2 ] ) are on the unit circle, provided that |Am| ≥ m ∑ k=0 |Ak −Am| = m−1 ∑ k=1 |Ak −Am|. Moreover, the zeros of Pm are near to the m + 1st roots of unity (except the root 1). A. Schinzel [3] g...
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