Results on the number of zeros in a disk for three types of polynomials
Author(s) -
Derek T Bryant,
Robert B. Gardner
Publication year - 2016
Publication title -
acta et commentationes universitatis tartuensis de mathematica
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.276
H-Index - 6
eISSN - 2228-4699
pISSN - 1406-2283
DOI - 10.12697/acutm.2016.20.12
Subject(s) - mathematics , combinatorics
We impose a monotonicity condition with several reversals on the moduli of the coefficients of a polynomial. We then consider three types of polynomials: (1) those satisfying the condition on all of the coefficients, (2) those satisfying the condition on the even indexed and odd indexed coefficients separately, and (3) polynomials of the form P(z) = a(0) + Sigma(n)(j=mu) a(j)z(j) where mu >= 1 with the coefficients a(mu), a(mu)+1, ..., a(n) satisfying the condition. For each type of polynomial, we give a result which puts a bound on the number of zeros in a disk (in the complex plane) centered at the origin. For each type, we give an example showing the results are best possible.
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