{"title":"Investigation of the Asymptotics of the Eigenvalues of a Second-Order Quasidifferential Boundary Value Problem","authors":"M. Yu. Vatolkin","doi":"10.3103/s1066369x24700154","DOIUrl":null,"url":null,"abstract":"<h3 data-test=\"abstract-sub-heading\">Abstract</h3><p>We construct the asymptotics of the eigenvalues for a quasidifferential Sturm–Liouville boundary value problem on eigenvalues and eigenfunctions considered on a segment <span>\\(J = [a,b]\\)</span>, with the boundary conditions of type I on the left and right, that is, for a problem of the form (in the explicit notation)\n<span>\\({{p}_{{22}}}(t)\\left( {{{p}_{{11}}}(t)\\left( {{{p}_{{00}}}(t)x(t)} \\right){\\kern 1pt} '\\; + {{p}_{{10}}}(t)\\left( {{{p}_{{00}}}(t)x(t)} \\right)} \\right){\\kern 1pt} '\\; + {{p}_{{21}}}(t)\\left( {{{p}_{{11}}}(t)\\left( {{{p}_{{00}}}(t)x(t)} \\right){\\kern 1pt} '\\; + {{p}_{{10}}}(t)\\left( {{{p}_{{00}}}(t)x(t)} \\right)} \\right)\\)</span>\n<span>\\( + \\;{{p}_{{20}}}(t)\\left( {{{p}_{{00}}}(t)x(t)} \\right) = - \\lambda \\left( {{{p}_{{00}}}(t)x(t)} \\right)\\;\\;(t \\in J = [a,b]),\\)</span>\n<span>\\({{p}_{{00}}}(a)x(a) = {{p}_{{00}}}(b)x(b) = 0.\\)</span>\nThe requirements for smoothness of the coefficients (that is, functions <span>\\({{p}_{{ik}}}( \\cdot ):J \\to \\mathbb{R}\\)</span>, <span>\\(k \\in 0:i\\)</span>, <span>\\(i \\in 0:2\\)</span>) in the equation are minimal, namely, these are as follows: the functions <span>\\({{p}_{{ik}}}( \\cdot ):J \\to \\mathbb{R}\\)</span> are such that the functions <span>\\({{p}_{{00}}}( \\cdot )\\)</span> and <span>\\({{p}_{{22}}}( \\cdot )\\)</span> are measurable, nonnegative, almost every finite, and almost everywhere nonzero and the functions <span>\\({{p}_{{11}}}( \\cdot )\\)</span> and <span>\\({{p}_{{21}}}( \\cdot )\\)</span> also are nonnegative on the segment <span>\\(J,\\)</span> and, in addition, the functions <span>\\({{p}_{{11}}}( \\cdot )\\)</span> and <span>\\({{p}_{{22}}}( \\cdot )\\)</span> are essentially bounded on <span>\\(J,\\)</span> the functions\n<span>\\(\\frac{1}{{{{p}_{{11}}}( \\cdot )}},\\;\\;\\frac{{{{p}_{{10}}}( \\cdot )}}{{{{p}_{{11}}}( \\cdot )}},\\;\\;\\frac{{{{p}_{{20}}}( \\cdot )}}{{{{p}_{{22}}}( \\cdot )}},\\;\\;\\frac{{{{p}_{{21}}}( \\cdot )}}{{{{p}_{{22}}}( \\cdot )}},\\;\\;\\frac{1}{{\\min \\{ {{p}_{{11}}}(t){{p}_{{22}}}(t),1\\} }}\\)</span>\nare summable on the segment <span>\\(J.\\)</span> The function <span>\\({{p}_{{20}}}( \\cdot )\\)</span> acts as a potential. It is proved that under the condition of nonoscillation of a homogeneous quasidifferential equation of the second order on <span>\\(J\\)</span>, the asymptotics of the eigenvalues of the boundary value problem under consideration has the form\n<span>\\({{\\lambda }_{k}} = {{(\\pi k)}^{2}}\\left( {D + O({\\text{1/}}{{k}^{2}})} \\right)\\)</span>\nas <span>\\(k \\to \\infty ,\\)</span> where <span>\\(D\\)</span> is a real positive constant defined in some way.</p>","PeriodicalId":46110,"journal":{"name":"Russian Mathematics","volume":"51 1","pages":""},"PeriodicalIF":0.5000,"publicationDate":"2024-06-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Russian Mathematics","FirstCategoryId":"1085","ListUrlMain":"https://doi.org/10.3103/s1066369x24700154","RegionNum":0,"RegionCategory":null,"ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q3","JCRName":"MATHEMATICS","Score":null,"Total":0}
引用次数: 0
Abstract
We construct the asymptotics of the eigenvalues for a quasidifferential Sturm–Liouville boundary value problem on eigenvalues and eigenfunctions considered on a segment \(J = [a,b]\), with the boundary conditions of type I on the left and right, that is, for a problem of the form (in the explicit notation)
\({{p}_{{22}}}(t)\left( {{{p}_{{11}}}(t)\left( {{{p}_{{00}}}(t)x(t)} \right){\kern 1pt} '\; + {{p}_{{10}}}(t)\left( {{{p}_{{00}}}(t)x(t)} \right)} \right){\kern 1pt} '\; + {{p}_{{21}}}(t)\left( {{{p}_{{11}}}(t)\left( {{{p}_{{00}}}(t)x(t)} \right){\kern 1pt} '\; + {{p}_{{10}}}(t)\left( {{{p}_{{00}}}(t)x(t)} \right)} \right)\)\( + \;{{p}_{{20}}}(t)\left( {{{p}_{{00}}}(t)x(t)} \right) = - \lambda \left( {{{p}_{{00}}}(t)x(t)} \right)\;\;(t \in J = [a,b]),\)\({{p}_{{00}}}(a)x(a) = {{p}_{{00}}}(b)x(b) = 0.\)
The requirements for smoothness of the coefficients (that is, functions \({{p}_{{ik}}}( \cdot ):J \to \mathbb{R}\), \(k \in 0:i\), \(i \in 0:2\)) in the equation are minimal, namely, these are as follows: the functions \({{p}_{{ik}}}( \cdot ):J \to \mathbb{R}\) are such that the functions \({{p}_{{00}}}( \cdot )\) and \({{p}_{{22}}}( \cdot )\) are measurable, nonnegative, almost every finite, and almost everywhere nonzero and the functions \({{p}_{{11}}}( \cdot )\) and \({{p}_{{21}}}( \cdot )\) also are nonnegative on the segment \(J,\) and, in addition, the functions \({{p}_{{11}}}( \cdot )\) and \({{p}_{{22}}}( \cdot )\) are essentially bounded on \(J,\) the functions
\(\frac{1}{{{{p}_{{11}}}( \cdot )}},\;\;\frac{{{{p}_{{10}}}( \cdot )}}{{{{p}_{{11}}}( \cdot )}},\;\;\frac{{{{p}_{{20}}}( \cdot )}}{{{{p}_{{22}}}( \cdot )}},\;\;\frac{{{{p}_{{21}}}( \cdot )}}{{{{p}_{{22}}}( \cdot )}},\;\;\frac{1}{{\min \{ {{p}_{{11}}}(t){{p}_{{22}}}(t),1\} }}\)
are summable on the segment \(J.\) The function \({{p}_{{20}}}( \cdot )\) acts as a potential. It is proved that under the condition of nonoscillation of a homogeneous quasidifferential equation of the second order on \(J\), the asymptotics of the eigenvalues of the boundary value problem under consideration has the form
\({{\lambda }_{k}} = {{(\pi k)}^{2}}\left( {D + O({\text{1/}}{{k}^{2}})} \right)\)
as \(k \to \infty ,\) where \(D\) is a real positive constant defined in some way.