Askey–Wilson polynomials

In mathematics, the Askey–Wilson polynomials (or q-Wilson polynomials) are a family of orthogonal polynomials introduced by Askey and Wilson (1985) as q-analogs of the Wilson polynomials. They include many of the other orthogonal polynomials in 1 variable as special or limiting cases, described in the Askey scheme. Askey–Wilson polynomials are the special case of Macdonald polynomials (or Koornwinder polynomials) for the non-reduced affine root system of type (C^∨
₁, C₁), and their 4 parameters a, b, c, d correspond to the 4 orbits of roots of this root system.

They are defined by

$p_n(x;a,b,c,d|q)=(ab,ac,ad;q{)}_n{a}^{-n}{}_4{\varphi }_3[\begin{array}{cccc}{q}^{-n}& abcd{q}^{n-1}& a{e}^{i\theta }& a{e}^{-i\theta }\\ ab& ac& ad\end{array};q,q]$

where ϕ is a basic hypergeometric function and x = cos(θ) and (,,,)_n is the q-Pochhammer symbol. Askey–Wilson functions are a generalization to non-integral values of n.

See also

• Askey scheme

References

• Askey, Richard; Wilson, James (1985), "Some basic hypergeometric orthogonal polynomials that generalize Jacobi polynomials", Memoirs of the American Mathematical Society, 54 (319): iv+55, doi:10.1090/memo/0319, ISBN 978-0-8218-2321-7, ISSN 0065-9266, MR 0783216
• Gasper, George; Rahman, Mizan (2004), Basic hypergeometric series, Encyclopedia of Mathematics and its Applications, 96 (2nd ed.), Cambridge University Press, ISBN 978-0-521-83357-8, MR 2128719
• Koornwinder, Tom H.; Wong, Roderick S. C.; Koekoek, Roelof; Swarttouw, René F. (2010), "Askey-Wilson class", 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
• Koornwinder, Tom H. (2012), "Askey-Wilson polynomial", Scholarpedia, 7 (7): 7761, doi:10.4249/scholarpedia.7761