Let W (ψ; x, y) be the wideband ambiguity function. It is obtained in this note that y− α+2 2 W (ψ;x, y)(α > −1) is SO(2)-invariant if and only if the Fourier transform of ψ is a Laguerre function.

We present a direct proof of a known result that the Hardy operator Hf(x) = 1 x R x 0 f(t) dt in the space L = L2(0,∞) can be written as H = I − U , where U is a shift operator (Uen = en+1, n ∈ Z) for some orthonormal basis {en}. The basis {en} is constructed by using classical Laguerre polynomials. We also explain connections with the Euler differential equation of the first order y′− 1 x y = ...

We consider the compressive wave for the modified Korteweg–de Vries equation with background constants c > 0 for x→ −∞ and 0 for x→ +∞. We study the asymptotics of solutions in the transition zone 4ct− εt < x < 4ct − βt ln t for ε > 0, σ ∈ (0, 1), β > 0. In this region we have a bulk of nonvanishing oscillations, the number of which grows as εt ln t . Also we show how to obtain Khruslov–Kotlyar...

We consider a varying discrete Sobolev inner product involving the Laguerre weight. Our aim is to study the asymptotic properties of the corresponding orthogonal polynomials and of their zeros. We are interested in Mehler–Heine type formulas because they describe the asymptotic differences between these Sobolev orthogonal polynomials and the classical Laguerre polynomials. Moreover, they give u...

This result was obtained also by N. Bari [1] using very different methods. The factor n in (1.1) cannot be replaced by any function tending to infinity more slowly. Namely, for each n exist polynomials P (t) of degree n such that the left side of (1.1) is ≤ Bn, where B is a constant of the same nature as A. Under only a little restriction on the zeros of P (z), M. A. Malik [4] found the followi...

Analysis of function spaces and special functions are closely related to the representation theory of Lie groups. We explain here the connection between the Laguerre functions, the Laguerre polynomials, and the Meixner-Pollacyck polynomials on the one side, and highest weight representations of Hermitian Lie groups on the other side. The representation theory is used to derive differential equa...

The explicit double sum for the associated Laguerre polynomials is derived combinatorially. The moments are described using certain statistics on permutations and permutation tableaux. Another derivation of the double sum is provided using only the moment generating function.

The support of the orthogonality measure of so-called little q-Laguerre polynomials {ln(.; a|q)}n=0, 0 < q < 1, 0 < a < q−1, is given by Sq = {1, q, q, . . .} ∪ {0}. Based on a method of MÃlotkowski and Szwarc we deduce a parameter set which admits nonnegative linearization. We additionally use this result to prove that little q-Laguerre polynomials constitute a so-called Faber basis in C(Sq).

—An explicit formula for the Fourier coef cients of the Legendre polynomials can be found in the Bateman Manuscript Project. However, formulas for more general classes of orthogonal polynomials do not appear to have been worked out. Here we derive explicit formulas for the Fourier series of Gegenbauer, Jacobi, Laguerre and Hermite polynomials. The methods described here apply in principle to an...