Article ID Journal Published Year Pages File Type
4608190 Journal of Approximation Theory 2007 12 Pages PDF
Abstract

Given a probability measure μ with infinite support on the unit circle ∂D={z:|z|=1}, we consider a sequence of paraorthogonal polynomials hn(z,λ) vanishing at z=λ where λ∈∂D is fixed. We prove that for any fixed z0∉supp(dμ) distinct from λ, we can find an explicit ρ>0 independent of n such that either hn or hn+1 (or both) has no zero inside the disk B(z0,ρ), with the possible exception of λ.Then we introduce paraorthogonal polynomials of the second kind, denoted sn(z,λ). We prove three results concerning sn and hn. First, we prove that zeros of sn and hn interlace. Second, for z0 an isolated point in supp(dμ), we find an explicit radius such that either sn or sn+1 (or both) have no zeros inside . Finally, we prove that for such z0 we can find an explicit radius such that either hn or hn+1 (or both) has at most one zero inside the ball .

Related Topics
Physical Sciences and Engineering Mathematics Analysis