Discrete q-Hermite polynomials

In mathematics, the discrete q-Hermite polynomials are two closely related families h_n(x;q) and ĥ_n(x;q) of basic hypergeometric orthogonal polynomials in the basic Askey scheme, introduced by Al-Salam and Carlitz (1965). Roelof Koekoek, Peter A. Lesky, and René F. Swarttouw (2010, 14) give a detailed list of their properties.

Definition

The discrete q-Hermite polynomials are given in terms of basic hypergeometric functions and the Al-Salam–Carlitz polynomials by

\displaystyle h_{n}(x;q)=q^{\binom {n}{2}}{}_{2}\phi _{1}(q^{-n},x^{-1};0;q,-qx)=x^{n}{}_{2}\phi _{0}(q^{-n},q^{-n+1};;q^{2},q^{2n-1}/x^{2})=U_{n}^{(-1)}(x;q)

\displaystyle {\hat {h}}_{n}(x;q)=i^{-n}q^{-{\binom {n}{2}}}{}_{2}\phi _{0}(q^{-n},ix;;q,-q^{n})=x^{n}{}_{2}\phi _{1}(q^{-n},q^{-n+1};0;q^{2},-q^{2}/x^{2})=i^{-n}V_{n}^{(-1)}(ix;q)

and are related by

h_{n}(ix;q^{-1})=i^{n}{\hat {h}}_{n}(x;q)

gollark: See, this is much nicer.

gollark: ```rustpub struct List<T> { head: Link<T>,}type Link<T> = Option<Box<Node<T>>>;struct Node<T> { elem: T, next: Link<T>,}impl<T> List<T> { pub fn new() -> Self { List { head: None } } pub fn push(&mut self, elem: T) { let new_node = Box::new(Node { elem: elem, next: self.head.take(), }); self.head = Some(new_node); } pub fn pop(&mut self) -> Option<T> { self.head.take().map(|node| { self.head = node.next; node.elem }) }}impl<T> Drop for List<T> { fn drop(&mut self) { let mut cur_link = self.head.take(); while let Some(mut boxed_node) = cur_link { cur_link = boxed_node.next.take(); } }}```

gollark: ... or at all?

gollark: You don't have a thing to efficiently deallocate the list.

gollark: Collections which work on a big chunk of memory or something *do* kind of have to use unsafe, linked lists or (some?) trees mostly don't.

References

Berg, Christian; Ismael, Mourad (1994), Q-Hermite Polynomials and Classical Orthogonal Polynomials, arXiv:math/9405213
Al-Salam, W. A.; Carlitz, L. (1965), "Some orthogonal q-polynomials", Mathematische Nachrichten, 30 (1–2): 47–61, doi:10.1002/mana.19650300105, ISSN 0025-584X, MR 0197804
Gasper, George; Rahman, Mizan (2004), Basic hypergeometric series, Encyclopedia of Mathematics and its Applications, 96 (2nd ed.), Cambridge University Press, doi:10.2277/0521833574, ISBN 978-0-521-83357-8, MR 2128719
Koekoek, Roelof; Lesky, Peter A.; Swarttouw, René F. (2010), Hypergeometric orthogonal polynomials and their q-analogues, Springer Monographs in Mathematics, Berlin, New York: Springer-Verlag, doi:10.1007/978-3-642-05014-5, ISBN 978-3-642-05013-8, MR 2656096
Koornwinder, Tom H.; Wong, Roderick S. C.; Koekoek, Roelof; Swarttouw, René F. (2010), "Chapter 18 Orthogonal Polynomials", in Olver, Frank W. J.; Lozier, Daniel M.; Boisvert, Ronald F.; Clark, Charles W. (eds.), NIST Handbook of Mathematical Functions, Cambridge University Press, ISBN 978-0-521-19225-5, MR 2723248

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