On the basis property of Riesz means of spectral expansions corresponding to a nonself-adjoint ordinary differential operator of higher order: I

2000 ◽  
Vol 36 (3) ◽  
pp. 337-348
Author(s):  
A. M. Zuev
2020 ◽  
Vol 19 ◽  

In this paper studied the convergence of spectral expansions of functions of the class W1 1 ( ) G ,G= ( ) 0,1 in eigenfunctions of an ordinary differential operator of third order with integral coefficients. Sufficient conditions for absolute and uniform convergence are obtained and the rate of uniform convergence of these expansions on the interval G is found.


Author(s):  
Richard C. Gilbert

SynopsisFormulas are determined for the deficiency numbers of a formally symmetric ordinary differential operator with complex coefficients which have asymptotic expansions of a prescribed type on a half-axis. An implication of these formulas is that for any given positive integer there exists a formally symmetric ordinary differential operator whose deficiency numbers differ by that positive integer.


Author(s):  
Abdizhahan Sarsenbi

In this work, we studied the Green’s functions of the second order differential operators with involution. Uniform equiconvergence of spectral expansions related to the second-order differential operators with involution is obtained. Basicity of eigenfunctions of the second-order differential operator operator with complex-valued coefficient is established.


2016 ◽  
Vol 60 (2) ◽  
pp. 451-460
Author(s):  
Andrey E. Mironov ◽  
Dafeng Zuo

AbstractThe Halphen operator is a third-order operator of the formwhere g ≠ 2 mod(3), where the Weierstrass ℘-function satisfies the equationIn the equianharmonic case, i.e. g2 = 0, the Halphen operator commutes with some ordinary differential operator Ln of order n ≠ 0 mod(3). In this paper we find the spectral curve of the pair L3, Ln.


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