Meanings of the first eigenfunctions of perturbed discrete operator with simple spectrum finding

In article received analitical formulas for finding first «weighted» corrections of the perturbation theory perturbed selfadjoint operators, when eigenvalues of unperturbed operators is simple. Received estimate of remainder of Rayleigh-Shredinger's sum of functional series. The method of finding of meanings of eigenfunctions of perturbed discrete operator with a simple spectrum is developed.