Let pm(x) = P (λ) m (x)/P (λ) m (1) be the m-th ultraspherical polynomial normalized by pm(1) = 1. We prove the inequality |x|pn(x)−pn−1(x)pn+1(x) ≥ 0, x ∈ [−1, 1], for −1/2 < λ ≤ 1/2. Equality holds only for x = ±1 and, if n is even, for x = 0. Further partial results on an extension of this inequality to normalized Jacobi polynomials are given.

A recently introduced fast algorithm for the computation of the first N terms in an expansion of an analytic function into ultraspherical polynomials consists of three steps: Firstly, each expansion coefficient is represented as a linear combination of derivatives; secondly, it is represented, using the Cauchy integral formula, as a contour integral of the function multiplied by a kernel; final...

We look for differential equations satisfied by the generalized Jacobi polynomials { P n (x) }∞ n=0 which are orthogonal on the interval [−1, 1] with respect to the weight function Γ(α+ β + 2) 2α+β+1Γ(α+ 1)Γ(β + 1) (1− x)(1 + x) +Mδ(x+ 1) +Nδ(x− 1), where α > −1, β > −1, M ≥ 0 and N ≥ 0. In the special case that β = α and N = M we find all differential equations of the form ∞ ∑ i=0 ci(x)y (x) =...