### Abstract

A few years ago the authors introduced a new approach to study asymptotic questions for orthogonal polynomials. In this paper we give an overview of our method and review the results which have been obtained in Deift et al. (Internat. Math. Res. Notices (1997) 759, Comm. Pure Appl. Math. 52 (1999) 1491, 1335), Deift (Orthogonal Polynomials and Random Matrices: A Riemann-Hilbert Approach, Courant Lecture Notes, Vol. 3, New York University, 1999), Kriecherbauer and McLaughlin (Internat. Math. Res. Notices (1999) 299) and Baik et al. (J. Amer. Math. Soc. 12 (1999) 1119). We mainly consider orthogonal polynomials with respect to weights on the real line which are either (1) Freud-type weights dα(x) = e^{-Q(x)} dx (Q polynomial or Q(x) = x^{β}, β>0), or (2) varying weights dα_{n}(x) = e^{-nV(x)} dx (V analytic, lim_{x→∞}V(x)/logx = ∞). We obtain Plancherel-Rotach-type asymptotics in the entire complex plane as well as asymptotic formulae with error estimates for the leading coefficients, for the recurrence coefficients, and for the zeros of the orthogonal polynomials. Our proof starts from an observation of Fokas et al. (Comm. Math. Phys. 142 (1991) 313) that the orthogonal polynomials can be determined as solutions of certain matrix valued Riemann-Hilbert problems. We analyze the Riemann-Hilbert problems by a steepest descent type method introduced by Deift and Zhou (Ann. Math. 137 (1993) 295) and further developed in Deift and Zhou (Comm. Pure Appl. Math. 48 (1995) 277) and Deift et al. (Proc. Nat. Acad. Sci. USA 95 (1998) 450). A crucial step in our analysis is the use of the well-known equilibrium measure which describes the asymptotic distribution of the zeros of the orthogonal polynomials.

Original language | English (US) |
---|---|

Pages (from-to) | 47-63 |

Number of pages | 17 |

Journal | Journal of Computational and Applied Mathematics |

Volume | 133 |

Issue number | 1-2 |

DOIs | |

State | Published - Aug 1 2001 |

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### Keywords

- Asymptotic analysis
- Freud weight
- Orthogonal polynomials
- Riemann-hilbert problem

### ASJC Scopus subject areas

- Applied Mathematics
- Computational Mathematics
- Numerical Analysis

### Cite this

*Journal of Computational and Applied Mathematics*,

*133*(1-2), 47-63. https://doi.org/10.1016/S0377-0427(00)00634-8

**A riemann-Hilbert approach to asymptotic questions for orthogonal polynomials.** / Deift, P.; Kriecherbauer, T.; Mclaughlin, Kenneth D T; Venakides, S.; Zhou, X.

Research output: Contribution to journal › Article

*Journal of Computational and Applied Mathematics*, vol. 133, no. 1-2, pp. 47-63. https://doi.org/10.1016/S0377-0427(00)00634-8

}

TY - JOUR

T1 - A riemann-Hilbert approach to asymptotic questions for orthogonal polynomials

AU - Deift, P.

AU - Kriecherbauer, T.

AU - Mclaughlin, Kenneth D T

AU - Venakides, S.

AU - Zhou, X.

PY - 2001/8/1

Y1 - 2001/8/1

N2 - A few years ago the authors introduced a new approach to study asymptotic questions for orthogonal polynomials. In this paper we give an overview of our method and review the results which have been obtained in Deift et al. (Internat. Math. Res. Notices (1997) 759, Comm. Pure Appl. Math. 52 (1999) 1491, 1335), Deift (Orthogonal Polynomials and Random Matrices: A Riemann-Hilbert Approach, Courant Lecture Notes, Vol. 3, New York University, 1999), Kriecherbauer and McLaughlin (Internat. Math. Res. Notices (1999) 299) and Baik et al. (J. Amer. Math. Soc. 12 (1999) 1119). We mainly consider orthogonal polynomials with respect to weights on the real line which are either (1) Freud-type weights dα(x) = e-Q(x) dx (Q polynomial or Q(x) = xβ, β>0), or (2) varying weights dαn(x) = e-nV(x) dx (V analytic, limx→∞V(x)/logx = ∞). We obtain Plancherel-Rotach-type asymptotics in the entire complex plane as well as asymptotic formulae with error estimates for the leading coefficients, for the recurrence coefficients, and for the zeros of the orthogonal polynomials. Our proof starts from an observation of Fokas et al. (Comm. Math. Phys. 142 (1991) 313) that the orthogonal polynomials can be determined as solutions of certain matrix valued Riemann-Hilbert problems. We analyze the Riemann-Hilbert problems by a steepest descent type method introduced by Deift and Zhou (Ann. Math. 137 (1993) 295) and further developed in Deift and Zhou (Comm. Pure Appl. Math. 48 (1995) 277) and Deift et al. (Proc. Nat. Acad. Sci. USA 95 (1998) 450). A crucial step in our analysis is the use of the well-known equilibrium measure which describes the asymptotic distribution of the zeros of the orthogonal polynomials.

AB - A few years ago the authors introduced a new approach to study asymptotic questions for orthogonal polynomials. In this paper we give an overview of our method and review the results which have been obtained in Deift et al. (Internat. Math. Res. Notices (1997) 759, Comm. Pure Appl. Math. 52 (1999) 1491, 1335), Deift (Orthogonal Polynomials and Random Matrices: A Riemann-Hilbert Approach, Courant Lecture Notes, Vol. 3, New York University, 1999), Kriecherbauer and McLaughlin (Internat. Math. Res. Notices (1999) 299) and Baik et al. (J. Amer. Math. Soc. 12 (1999) 1119). We mainly consider orthogonal polynomials with respect to weights on the real line which are either (1) Freud-type weights dα(x) = e-Q(x) dx (Q polynomial or Q(x) = xβ, β>0), or (2) varying weights dαn(x) = e-nV(x) dx (V analytic, limx→∞V(x)/logx = ∞). We obtain Plancherel-Rotach-type asymptotics in the entire complex plane as well as asymptotic formulae with error estimates for the leading coefficients, for the recurrence coefficients, and for the zeros of the orthogonal polynomials. Our proof starts from an observation of Fokas et al. (Comm. Math. Phys. 142 (1991) 313) that the orthogonal polynomials can be determined as solutions of certain matrix valued Riemann-Hilbert problems. We analyze the Riemann-Hilbert problems by a steepest descent type method introduced by Deift and Zhou (Ann. Math. 137 (1993) 295) and further developed in Deift and Zhou (Comm. Pure Appl. Math. 48 (1995) 277) and Deift et al. (Proc. Nat. Acad. Sci. USA 95 (1998) 450). A crucial step in our analysis is the use of the well-known equilibrium measure which describes the asymptotic distribution of the zeros of the orthogonal polynomials.

KW - Asymptotic analysis

KW - Freud weight

KW - Orthogonal polynomials

KW - Riemann-hilbert problem

UR - http://www.scopus.com/inward/record.url?scp=0035417833&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=0035417833&partnerID=8YFLogxK

U2 - 10.1016/S0377-0427(00)00634-8

DO - 10.1016/S0377-0427(00)00634-8

M3 - Article

AN - SCOPUS:0035417833

VL - 133

SP - 47

EP - 63

JO - Journal of Computational and Applied Mathematics

JF - Journal of Computational and Applied Mathematics

SN - 0377-0427

IS - 1-2

ER -