This paper is devoted to investigating the uniform convergence conditions of Fourier series expansions continuous functions in terms eigenfunctions a Sturm-Liouville problem with eigenparameter one boundary on closed interval. Such problems are quite common mathematical physics problems.

In this paper we apply a minmax characterization for nonoverdamped nonlinear eigenvalue problems to a rational eigenproblem governing mechanical vibrations of a tube bundle immersed in an inviscid compressible fluid. This eigenproblem is nonstandard in two respects: it depends rationally on the eigenparameter, and it involves non-local boundary conditions. Comparison results are proved comparin...

where (pn) and (qn), n ∈ Z are real sequences, and λ is an eigenparameter. We find a polynomial type Jost solution of this BVP. Then we investigate the analytical properties and asymptotic behavior of the Jost solution. Using the Weyl compact perturbation theorem, we prove that a self-adjoint discrete Dirac system has a continuous spectrum filling the segment [–2, 2]. We also prove that the Dir...

We employ an operator theoretic setting established in [2]. Under Condition 2.1 below, a self-adjoint (actually quasi-uniformly positive [7]) operator A in the Krein space L2,r(−1, 1)⊕C 2 ∆ is associated with the eigenvalue problem (1.1), (1.2). Here ∆ is a 2 × 2 nonsingular Hermitean matrix which is determined by M and N; see Section 2 for details. We remark that the topology of this Krein spa...