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On the difference equations with periodic coefficients

Mathematical Physics 2007-05-23 v1 Complex Variables math.MP

Abstract

In this paper, we study entire solutions of the difference equation ψ(z+h)=M(z)ψ(z)\psi(z+h)=M(z)\psi(z), zCz\in{\mathbb C}, ψ(z)C2\psi(z)\in {\mathbb C}^2. In this equation, hh is a fixed positive parameter and M:CSL(2,C)M: {\mathbb C}\to SL(2,{\mathbb C}) is a given matrix function. We assume that M(z)M(z) is a 2π2\pi-periodic trigonometric polynomial. We construct the minimal entire solutions, i.e. entire solutions with the minimal possible growth simultaneously as for imz+z\to+\infty so for imzz\to-\infty. We show that the monodromy matrices corresponding to the minimal entire solutions are trigonometric polynomials of the same order as MM. This property relates the spectral analysis of difference Schr\"odinger equations with trigonometric polynomial coefficients to an analysis of finite dimensional dynamical systems.

Cite

@article{arxiv.math-ph/0206020,
  title  = {On the difference equations with periodic coefficients},
  author = {Vladimir Buslaev and Alexander Fedotov},
  journal= {arXiv preprint arXiv:math-ph/0206020},
  year   = {2007}
}

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45 pages