{"title":"在 $0le x \\le 1$ 的区间内对 $x^m (-\\log x)^l$ 进行切比雪夫近似计算","authors":"Richard J. Mathar","doi":"arxiv-2408.15212","DOIUrl":null,"url":null,"abstract":"The series expansion of $x^m (-\\log x)^l$ in terms of the shifted Chebyshev\nPolynomials $T_n^*(x)$ requires evaluation of the integral family $\\int_0^1 x^m\n(-\\log x)^l dx / \\sqrt{x-x^2}$. We demonstrate that these can be reduced by\npartial integration to sums over integrals with exponent $m=0$ which have known\nrepresentations as finite sums over polygamma functions.","PeriodicalId":501145,"journal":{"name":"arXiv - MATH - Classical Analysis and ODEs","volume":"64 1","pages":""},"PeriodicalIF":0.0000,"publicationDate":"2024-08-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":"{\"title\":\"Chebyshev approximation of $x^m (-\\\\log x)^l$ in the interval $0\\\\le x \\\\le 1$\",\"authors\":\"Richard J. Mathar\",\"doi\":\"arxiv-2408.15212\",\"DOIUrl\":null,\"url\":null,\"abstract\":\"The series expansion of $x^m (-\\\\log x)^l$ in terms of the shifted Chebyshev\\nPolynomials $T_n^*(x)$ requires evaluation of the integral family $\\\\int_0^1 x^m\\n(-\\\\log x)^l dx / \\\\sqrt{x-x^2}$. We demonstrate that these can be reduced by\\npartial integration to sums over integrals with exponent $m=0$ which have known\\nrepresentations as finite sums over polygamma functions.\",\"PeriodicalId\":501145,\"journal\":{\"name\":\"arXiv - MATH - Classical Analysis and ODEs\",\"volume\":\"64 1\",\"pages\":\"\"},\"PeriodicalIF\":0.0000,\"publicationDate\":\"2024-08-27\",\"publicationTypes\":\"Journal Article\",\"fieldsOfStudy\":null,\"isOpenAccess\":false,\"openAccessPdf\":\"\",\"citationCount\":\"0\",\"resultStr\":null,\"platform\":\"Semanticscholar\",\"paperid\":null,\"PeriodicalName\":\"arXiv - MATH - Classical Analysis and ODEs\",\"FirstCategoryId\":\"1085\",\"ListUrlMain\":\"https://doi.org/arxiv-2408.15212\",\"RegionNum\":0,\"RegionCategory\":null,\"ArticlePicture\":[],\"TitleCN\":null,\"AbstractTextCN\":null,\"PMCID\":null,\"EPubDate\":\"\",\"PubModel\":\"\",\"JCR\":\"\",\"JCRName\":\"\",\"Score\":null,\"Total\":0}","platform":"Semanticscholar","paperid":null,"PeriodicalName":"arXiv - MATH - Classical Analysis and ODEs","FirstCategoryId":"1085","ListUrlMain":"https://doi.org/arxiv-2408.15212","RegionNum":0,"RegionCategory":null,"ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"","JCRName":"","Score":null,"Total":0}
Chebyshev approximation of $x^m (-\log x)^l$ in the interval $0\le x \le 1$
The series expansion of $x^m (-\log x)^l$ in terms of the shifted Chebyshev
Polynomials $T_n^*(x)$ requires evaluation of the integral family $\int_0^1 x^m
(-\log x)^l dx / \sqrt{x-x^2}$. We demonstrate that these can be reduced by
partial integration to sums over integrals with exponent $m=0$ which have known
representations as finite sums over polygamma functions.