A SAMPLING THEOREM ASSOCIATED WITH A QUADRATIC PENCIL OF STURM-LIOUVILLE OPERATORS WITH PERIODIC COEFFICIENTS

Kramer has developed a sampling theorem associated with n-th order self-adjoint differential operators. Recently this relation has been well developed. But the common property of the vast majority of papers is that the investigated boundary value problems have a simple eigenvalues. This paper is concerned with the application of the Kramer sampling theorem to a quadratic pencil of Sturm-Liouville operators with periodic coefficients. Such an operator may have multiple eigenvalues.