2020/11/30 by D. R. Yafaev, Yafaev, D. R.
Mathematics · #Spectral Theory in Mathematical Physics #Mathematical functions and polynomials #Numerical methods in inverse problems
paper · pdf · doi:10.48550/arxiv.2011.14987
Orthogonal polynomials Pn(λ) are oscillating functions of n as n→∞ for λ in the absolutely continuous spectrum of the corresponding Jacobi operator J. We show that, irrespective of any specific assumptions on coefficients of the operator J, amplitude and phase factors in asymptotic formulas for Pn(λ) are linked by certain universal relations found in the paper. Our approach relies on a study of operators diagonalizing Jacobi operators. Diagonalizing operators are constructed in terms of orthogonal polynomials Pn(λ). They act from the space L2 (\Bbb R) of functions into the space ℓ2 (\Bbb Z+) of sequences. We consider such operators in a rather general setting and find necessary and sufficient conditions of their boundedness.