An equilibrium problem for the limiting eigenvalue distribution of banded Toeplitz matrices. (English) Zbl 1185.15008
Summary: We study the limiting eigenvalue distribution of \(n \times n\) banded Toeplitz matrices as \(n \to \infty\). From classical results of P. Schmidt and F. Spitzer [Math. Scand. 8, 15–38 (1960; Zbl 0101.09203)], and I. I. Hirschman jun. [Ill. J. Math. 11, 145–159 (1967; Zbl 0144.38501)] it is known that the eigenvalues accumulate on a special curve in the complex plane and the normalized eigenvalue counting measure converges weakly to a measure on this curve as \(n \to\infty\). In this paper, we characterize the limiting measure in terms of an equilibrium problem. The limiting measure is one component of the unique vector of measures that minimizes an energy functional defined on admissible vectors of measures. In addition, we show that each of the other components is the limiting measure of the normalized counting measure on certain generalized eigenvalues.
MSC:
15A18 | Eigenvalues, singular values, and eigenvectors |
30E20 | Integration, integrals of Cauchy type, integral representations of analytic functions in the complex plane |
31A99 | Two-dimensional potential theory |
47B06 | Riesz operators; eigenvalue distributions; approximation numbers, \(s\)-numbers, Kolmogorov numbers, entropy numbers, etc. of operators |