Some properties of eigenfunctions of a fourth-order differential operator with discontinuous coefficients. (Russian)статья
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Дата последнего поиска статьи во внешних источниках: 16 января 2019 г.
Аннотация:The author considers the problem of eigenvalues and eigenfunctions of the operator Lu = (pu′′)′′ +(ru′)′ + qu, which is defined on an interval (a,b). The functions p, r, q are smooth functions in (a,b)\{x0} where x0 is a fixed point of the interval (a,b).
The author proves the formula for the mean value, with center at the point x0, of the eigenfunction u which corresponds to the eigenvalue λ, and gives the estimate sum n=1 +infty (u^2(x))n/(\sqrt[4](lambda n))^(1+delta) = O(1) forall delta > 0. This estimate is uniform in x on every compactum in (a,b).