{"title":"广义贝塞尔多项式单位圆上的正交权重","authors":"Sergey M. Zagorodnyuk","doi":"10.1016/j.jat.2024.106115","DOIUrl":null,"url":null,"abstract":"<div><div>In this paper we study the generalized Bessel polynomials <span><math><mrow><msub><mrow><mi>y</mi></mrow><mrow><mi>n</mi></mrow></msub><mrow><mo>(</mo><mi>x</mi><mo>,</mo><mi>a</mi><mo>,</mo><mi>b</mi><mo>)</mo></mrow></mrow></math></span> (in the notation of Krall and Frink). Let <span><math><mrow><mi>a</mi><mo>></mo><mn>1</mn></mrow></math></span>, <span><math><mrow><mi>b</mi><mo>∈</mo><mrow><mo>(</mo><mo>−</mo><mn>1</mn><mo>/</mo><mn>3</mn><mo>,</mo><mn>1</mn><mo>/</mo><mn>3</mn><mo>)</mo></mrow><mo>∖</mo><mrow><mo>{</mo><mn>0</mn><mo>}</mo></mrow></mrow></math></span>. In this case we present the following positive continuous weights <span><math><mrow><mi>p</mi><mrow><mo>(</mo><mi>θ</mi><mo>)</mo></mrow><mo>=</mo><mi>p</mi><mrow><mo>(</mo><mi>θ</mi><mo>,</mo><mi>a</mi><mo>,</mo><mi>b</mi><mo>)</mo></mrow></mrow></math></span> on the unit circle for <span><math><mrow><msub><mrow><mi>y</mi></mrow><mrow><mi>n</mi></mrow></msub><mrow><mo>(</mo><mi>x</mi><mo>,</mo><mi>a</mi><mo>,</mo><mi>b</mi><mo>)</mo></mrow></mrow></math></span>: <span><math><mrow><mn>2</mn><mi>π</mi><mi>p</mi><mrow><mo>(</mo><mi>θ</mi><mo>,</mo><mi>a</mi><mo>,</mo><mi>b</mi><mo>)</mo></mrow><mo>=</mo><mo>−</mo><mn>1</mn><mo>+</mo><mn>2</mn><mrow><mo>(</mo><mi>a</mi><mo>−</mo><mn>1</mn><mo>)</mo></mrow><msubsup><mrow><mo>∫</mo></mrow><mrow><mn>0</mn></mrow><mrow><mn>1</mn></mrow></msubsup><msup><mrow><mi>e</mi></mrow><mrow><mo>−</mo><mi>b</mi><mi>u</mi><mo>cos</mo><mi>θ</mi></mrow></msup><mo>cos</mo><mrow><mo>(</mo><mi>b</mi><mi>u</mi><mo>sin</mo><mi>θ</mi><mo>)</mo></mrow><msup><mrow><mrow><mo>(</mo><mn>1</mn><mo>−</mo><mi>u</mi><mo>)</mo></mrow></mrow><mrow><mi>a</mi><mo>−</mo><mn>2</mn></mrow></msup><mi>d</mi><mi>u</mi><mo>,</mo></mrow></math></span> where <span><math><mrow><mi>θ</mi><mo>∈</mo><mrow><mo>[</mo><mn>0</mn><mo>,</mo><mn>2</mn><mi>π</mi><mo>]</mo></mrow></mrow></math></span>. Namely, we have <span><math><mrow><msubsup><mrow><mo>∫</mo></mrow><mrow><mn>0</mn></mrow><mrow><mn>2</mn><mi>π</mi></mrow></msubsup><msub><mrow><mi>y</mi></mrow><mrow><mi>n</mi></mrow></msub><mrow><mo>(</mo><msup><mrow><mi>e</mi></mrow><mrow><mi>i</mi><mi>θ</mi></mrow></msup><mo>,</mo><mi>a</mi><mo>,</mo><mi>b</mi><mo>)</mo></mrow><msub><mrow><mi>y</mi></mrow><mrow><mi>m</mi></mrow></msub><mrow><mo>(</mo><msup><mrow><mi>e</mi></mrow><mrow><mi>i</mi><mi>θ</mi></mrow></msup><mo>,</mo><mi>a</mi><mo>,</mo><mi>b</mi><mo>)</mo></mrow><mi>p</mi><mrow><mo>(</mo><mi>θ</mi><mo>,</mo><mi>a</mi><mo>,</mo><mi>b</mi><mo>)</mo></mrow><mi>d</mi><mi>θ</mi><mo>=</mo><msub><mrow><mi>C</mi></mrow><mrow><mi>n</mi></mrow></msub><msub><mrow><mi>δ</mi></mrow><mrow><mi>n</mi><mo>,</mo><mi>m</mi></mrow></msub><mo>,</mo><mspace></mspace><msub><mrow><mi>C</mi></mrow><mrow><mi>n</mi></mrow></msub><mo>≠</mo><mn>0</mn><mo>,</mo><mspace></mspace><mi>n</mi><mo>,</mo><mi>m</mi><mo>=</mo><mn>0</mn><mo>,</mo><mn>1</mn><mo>,</mo><mn>2</mn><mo>,</mo><mo>…</mo><mo>.</mo></mrow></math></span> Notice that this orthogonality differs from the usual one for orthogonal polynomials on the unit circle. Some applications of the above orthogonality are given.</div></div>","PeriodicalId":54878,"journal":{"name":"Journal of Approximation Theory","volume":null,"pages":null},"PeriodicalIF":0.9000,"publicationDate":"2024-10-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":"{\"title\":\"Positive orthogonalizing weights on the unit circle for the generalized Bessel polynomials\",\"authors\":\"Sergey M. Zagorodnyuk\",\"doi\":\"10.1016/j.jat.2024.106115\",\"DOIUrl\":null,\"url\":null,\"abstract\":\"<div><div>In this paper we study the generalized Bessel polynomials <span><math><mrow><msub><mrow><mi>y</mi></mrow><mrow><mi>n</mi></mrow></msub><mrow><mo>(</mo><mi>x</mi><mo>,</mo><mi>a</mi><mo>,</mo><mi>b</mi><mo>)</mo></mrow></mrow></math></span> (in the notation of Krall and Frink). Let <span><math><mrow><mi>a</mi><mo>></mo><mn>1</mn></mrow></math></span>, <span><math><mrow><mi>b</mi><mo>∈</mo><mrow><mo>(</mo><mo>−</mo><mn>1</mn><mo>/</mo><mn>3</mn><mo>,</mo><mn>1</mn><mo>/</mo><mn>3</mn><mo>)</mo></mrow><mo>∖</mo><mrow><mo>{</mo><mn>0</mn><mo>}</mo></mrow></mrow></math></span>. In this case we present the following positive continuous weights <span><math><mrow><mi>p</mi><mrow><mo>(</mo><mi>θ</mi><mo>)</mo></mrow><mo>=</mo><mi>p</mi><mrow><mo>(</mo><mi>θ</mi><mo>,</mo><mi>a</mi><mo>,</mo><mi>b</mi><mo>)</mo></mrow></mrow></math></span> on the unit circle for <span><math><mrow><msub><mrow><mi>y</mi></mrow><mrow><mi>n</mi></mrow></msub><mrow><mo>(</mo><mi>x</mi><mo>,</mo><mi>a</mi><mo>,</mo><mi>b</mi><mo>)</mo></mrow></mrow></math></span>: <span><math><mrow><mn>2</mn><mi>π</mi><mi>p</mi><mrow><mo>(</mo><mi>θ</mi><mo>,</mo><mi>a</mi><mo>,</mo><mi>b</mi><mo>)</mo></mrow><mo>=</mo><mo>−</mo><mn>1</mn><mo>+</mo><mn>2</mn><mrow><mo>(</mo><mi>a</mi><mo>−</mo><mn>1</mn><mo>)</mo></mrow><msubsup><mrow><mo>∫</mo></mrow><mrow><mn>0</mn></mrow><mrow><mn>1</mn></mrow></msubsup><msup><mrow><mi>e</mi></mrow><mrow><mo>−</mo><mi>b</mi><mi>u</mi><mo>cos</mo><mi>θ</mi></mrow></msup><mo>cos</mo><mrow><mo>(</mo><mi>b</mi><mi>u</mi><mo>sin</mo><mi>θ</mi><mo>)</mo></mrow><msup><mrow><mrow><mo>(</mo><mn>1</mn><mo>−</mo><mi>u</mi><mo>)</mo></mrow></mrow><mrow><mi>a</mi><mo>−</mo><mn>2</mn></mrow></msup><mi>d</mi><mi>u</mi><mo>,</mo></mrow></math></span> where <span><math><mrow><mi>θ</mi><mo>∈</mo><mrow><mo>[</mo><mn>0</mn><mo>,</mo><mn>2</mn><mi>π</mi><mo>]</mo></mrow></mrow></math></span>. Namely, we have <span><math><mrow><msubsup><mrow><mo>∫</mo></mrow><mrow><mn>0</mn></mrow><mrow><mn>2</mn><mi>π</mi></mrow></msubsup><msub><mrow><mi>y</mi></mrow><mrow><mi>n</mi></mrow></msub><mrow><mo>(</mo><msup><mrow><mi>e</mi></mrow><mrow><mi>i</mi><mi>θ</mi></mrow></msup><mo>,</mo><mi>a</mi><mo>,</mo><mi>b</mi><mo>)</mo></mrow><msub><mrow><mi>y</mi></mrow><mrow><mi>m</mi></mrow></msub><mrow><mo>(</mo><msup><mrow><mi>e</mi></mrow><mrow><mi>i</mi><mi>θ</mi></mrow></msup><mo>,</mo><mi>a</mi><mo>,</mo><mi>b</mi><mo>)</mo></mrow><mi>p</mi><mrow><mo>(</mo><mi>θ</mi><mo>,</mo><mi>a</mi><mo>,</mo><mi>b</mi><mo>)</mo></mrow><mi>d</mi><mi>θ</mi><mo>=</mo><msub><mrow><mi>C</mi></mrow><mrow><mi>n</mi></mrow></msub><msub><mrow><mi>δ</mi></mrow><mrow><mi>n</mi><mo>,</mo><mi>m</mi></mrow></msub><mo>,</mo><mspace></mspace><msub><mrow><mi>C</mi></mrow><mrow><mi>n</mi></mrow></msub><mo>≠</mo><mn>0</mn><mo>,</mo><mspace></mspace><mi>n</mi><mo>,</mo><mi>m</mi><mo>=</mo><mn>0</mn><mo>,</mo><mn>1</mn><mo>,</mo><mn>2</mn><mo>,</mo><mo>…</mo><mo>.</mo></mrow></math></span> Notice that this orthogonality differs from the usual one for orthogonal polynomials on the unit circle. Some applications of the above orthogonality are given.</div></div>\",\"PeriodicalId\":54878,\"journal\":{\"name\":\"Journal of Approximation Theory\",\"volume\":null,\"pages\":null},\"PeriodicalIF\":0.9000,\"publicationDate\":\"2024-10-22\",\"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/S0021904524001035\",\"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/S0021904524001035","RegionNum":3,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q2","JCRName":"MATHEMATICS","Score":null,"Total":0}
Positive orthogonalizing weights on the unit circle for the generalized Bessel polynomials
In this paper we study the generalized Bessel polynomials (in the notation of Krall and Frink). Let , . In this case we present the following positive continuous weights on the unit circle for : where . Namely, we have Notice that this orthogonality differs from the usual one for orthogonal polynomials on the unit circle. Some applications of the above orthogonality are given.
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.