{"title":"受电弓方程的Jacobi-theta函数分析研究","authors":"Changgui Zhang","doi":"10.1016/j.jat.2023.105974","DOIUrl":null,"url":null,"abstract":"<div><p>The aim of this paper is to use the analytic theory of linear <span><math><mi>q</mi></math></span>-difference equations for the study of the functional-differential equation <span><math><mrow><msup><mrow><mi>y</mi></mrow><mrow><mo>′</mo></mrow></msup><mrow><mo>(</mo><mi>x</mi><mo>)</mo></mrow><mo>=</mo><mi>a</mi><mi>y</mi><mrow><mo>(</mo><mi>q</mi><mi>x</mi><mo>)</mo></mrow><mo>+</mo><mi>b</mi><mi>y</mi><mrow><mo>(</mo><mi>x</mi><mo>)</mo></mrow></mrow></math></span>, where <span><math><mi>a</mi></math></span> and <span><math><mi>b</mi></math></span> are two non-zero real or complex numbers. When <span><math><mrow><mn>0</mn><mo><</mo><mi>q</mi><mo><</mo><mn>1</mn></mrow></math></span> and <span><math><mrow><mi>y</mi><mrow><mo>(</mo><mn>0</mn><mo>)</mo></mrow><mo>=</mo><mn>1</mn></mrow></math></span><span>, the associated Cauchy problem admits a unique power series solution, </span><span><math><mrow><msub><mrow><mo>∑</mo></mrow><mrow><mi>n</mi><mo>≥</mo><mn>0</mn></mrow></msub><mfrac><mrow><msub><mrow><mrow><mo>(</mo><mo>−</mo><mi>a</mi><mo>/</mo><mi>b</mi><mo>;</mo><mi>q</mi><mo>)</mo></mrow></mrow><mrow><mi>n</mi></mrow></msub></mrow><mrow><mi>n</mi><mo>!</mo></mrow></mfrac><mspace></mspace><msup><mrow><mrow><mo>(</mo><mi>b</mi><mi>x</mi><mo>)</mo></mrow></mrow><mrow><mi>n</mi></mrow></msup></mrow></math></span>, that converges in the whole complex <span><math><mi>x</mi></math></span><span>-plane. The principal result obtained in the paper explains how to express this entire function solution into a linear combination<span><span> of solutions at infinity with the help of integral representations involving Jacobi theta functions. As a by-product, this connection formula between zero and infinity allows one to rediscover the classic theorem of Kato and McLeod on the </span>asymptotic behavior of the solutions over the real axis.</span></span></p></div>","PeriodicalId":54878,"journal":{"name":"Journal of Approximation Theory","volume":null,"pages":null},"PeriodicalIF":0.9000,"publicationDate":"2023-09-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":"{\"title\":\"Analytical study of the pantograph equation using Jacobi theta functions\",\"authors\":\"Changgui Zhang\",\"doi\":\"10.1016/j.jat.2023.105974\",\"DOIUrl\":null,\"url\":null,\"abstract\":\"<div><p>The aim of this paper is to use the analytic theory of linear <span><math><mi>q</mi></math></span>-difference equations for the study of the functional-differential equation <span><math><mrow><msup><mrow><mi>y</mi></mrow><mrow><mo>′</mo></mrow></msup><mrow><mo>(</mo><mi>x</mi><mo>)</mo></mrow><mo>=</mo><mi>a</mi><mi>y</mi><mrow><mo>(</mo><mi>q</mi><mi>x</mi><mo>)</mo></mrow><mo>+</mo><mi>b</mi><mi>y</mi><mrow><mo>(</mo><mi>x</mi><mo>)</mo></mrow></mrow></math></span>, where <span><math><mi>a</mi></math></span> and <span><math><mi>b</mi></math></span> are two non-zero real or complex numbers. When <span><math><mrow><mn>0</mn><mo><</mo><mi>q</mi><mo><</mo><mn>1</mn></mrow></math></span> and <span><math><mrow><mi>y</mi><mrow><mo>(</mo><mn>0</mn><mo>)</mo></mrow><mo>=</mo><mn>1</mn></mrow></math></span><span>, the associated Cauchy problem admits a unique power series solution, </span><span><math><mrow><msub><mrow><mo>∑</mo></mrow><mrow><mi>n</mi><mo>≥</mo><mn>0</mn></mrow></msub><mfrac><mrow><msub><mrow><mrow><mo>(</mo><mo>−</mo><mi>a</mi><mo>/</mo><mi>b</mi><mo>;</mo><mi>q</mi><mo>)</mo></mrow></mrow><mrow><mi>n</mi></mrow></msub></mrow><mrow><mi>n</mi><mo>!</mo></mrow></mfrac><mspace></mspace><msup><mrow><mrow><mo>(</mo><mi>b</mi><mi>x</mi><mo>)</mo></mrow></mrow><mrow><mi>n</mi></mrow></msup></mrow></math></span>, that converges in the whole complex <span><math><mi>x</mi></math></span><span>-plane. The principal result obtained in the paper explains how to express this entire function solution into a linear combination<span><span> of solutions at infinity with the help of integral representations involving Jacobi theta functions. As a by-product, this connection formula between zero and infinity allows one to rediscover the classic theorem of Kato and McLeod on the </span>asymptotic behavior of the solutions over the real axis.</span></span></p></div>\",\"PeriodicalId\":54878,\"journal\":{\"name\":\"Journal of Approximation Theory\",\"volume\":null,\"pages\":null},\"PeriodicalIF\":0.9000,\"publicationDate\":\"2023-09-24\",\"publicationTypes\":\"Journal Article\",\"fieldsOfStudy\":null,\"isOpenAccess\":false,\"openAccessPdf\":\"\",\"citationCount\":\"0\",\"resultStr\":null,\"platform\":\"Semanticscholar\",\"paperid\":null,\"PeriodicalName\":\"Journal of Approximation Theory\",\"FirstCategoryId\":\"100\",\"ListUrlMain\":\"https://www.sciencedirect.com/science/article/pii/S0021904523001120\",\"RegionNum\":3,\"RegionCategory\":\"数学\",\"ArticlePicture\":[],\"TitleCN\":null,\"AbstractTextCN\":null,\"PMCID\":null,\"EPubDate\":\"\",\"PubModel\":\"\",\"JCR\":\"Q2\",\"JCRName\":\"MATHEMATICS\",\"Score\":null,\"Total\":0}","platform":"Semanticscholar","paperid":null,"PeriodicalName":"Journal of Approximation Theory","FirstCategoryId":"100","ListUrlMain":"https://www.sciencedirect.com/science/article/pii/S0021904523001120","RegionNum":3,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q2","JCRName":"MATHEMATICS","Score":null,"Total":0}
Analytical study of the pantograph equation using Jacobi theta functions
The aim of this paper is to use the analytic theory of linear -difference equations for the study of the functional-differential equation , where and are two non-zero real or complex numbers. When and , the associated Cauchy problem admits a unique power series solution, , that converges in the whole complex -plane. The principal result obtained in the paper explains how to express this entire function solution into a linear combination of solutions at infinity with the help of integral representations involving Jacobi theta functions. As a by-product, this connection formula between zero and infinity allows one to rediscover the classic theorem of Kato and McLeod on the asymptotic behavior of the solutions over the real axis.
期刊介绍:
The Journal of Approximation Theory is devoted to advances in pure and applied approximation theory and related areas. These areas include, among others:
• Classical approximation
• Abstract approximation
• Constructive approximation
• Degree of approximation
• Fourier expansions
• Interpolation of operators
• General orthogonal systems
• Interpolation and quadratures
• Multivariate approximation
• Orthogonal polynomials
• Padé approximation
• Rational approximation
• Spline functions of one and several variables
• Approximation by radial basis functions in Euclidean spaces, on spheres, and on more general manifolds
• Special functions with strong connections to classical harmonic analysis, orthogonal polynomial, and approximation theory (as opposed to combinatorics, number theory, representation theory, generating functions, formal theory, and so forth)
• Approximation theoretic aspects of real or complex function theory, function theory, difference or differential equations, function spaces, or harmonic analysis
• Wavelet Theory and its applications in signal and image processing, and in differential equations with special emphasis on connections between wavelet theory and elements of approximation theory (such as approximation orders, Besov and Sobolev spaces, and so forth)
• Gabor (Weyl-Heisenberg) expansions and sampling theory.