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32 Painlevé TranscendentsApplications

§32.15 Orthogonal Polynomials

Let p_{n}(\xi), n=0,1,\dots, be the orthonormal set of polynomials defined by

with recurrence relation

32.15.2 a_{n+1}(z)p_{n+1}(\xi)=\xi p_{n}(\xi)-a_{n}(z)p_{n-1}(\xi),

for n=1,2,\dots; compare §18.2. Then u_{n}(z)=(a_{n}(z))^{2} satisfies the nonlinear recurrence relation

32.15.3 (u_{n+1}+u_{n}+u_{n-1})u_{n}=n-2zu_{n},

for n=1,2,\dots, and also \mbox{P}_{\mbox{\scriptsize IV}} with \alpha=-\tfrac{1}{2}n and \beta=-\tfrac{1}{2}n^{2}.

For this result and applications see Fokas et al. (1991): in this reference, on the right-hand side of Eq. (1.10), (n+\gamma)^{2} should be replaced by n+\gamma at its first appearance. See also Freud (1976), Brézin et al. (1978), Fokas et al. (1992), and Magnus (1995).