用三角多项式逼近连续周期函数的问题

Q4 Mathematics Researches in Mathematics Pub Date : 2021-10-06 DOI:10.15421/247711
V. Shalaev
{"title":"用三角多项式逼近连续周期函数的问题","authors":"V. Shalaev","doi":"10.15421/247711","DOIUrl":null,"url":null,"abstract":"In the paper, it is proved that$$1 - \\frac{1}{2n} \\leqslant \\sup\\limits_{\\substack{f \\in C\\\\f \\ne const}} \\frac{E_n(f)_C}{\\omega_2(f; \\pi/n)_C} \\leqslant \\inf\\limits_{L_n \\in Z_n(C)} \\sup\\limits_{\\substack{f \\in C\\\\f \\ne const}} \\frac{\\| f - L_n(f) \\|_C}{\\omega_2 (f; \\pi/n)_C} \\leqslant 1$$where $\\omega_2(f; t)_C$ is the modulus of smoothness of the function $f \\in C$, $E_n(f)_C$ is the best approximation by trigonometric polynomials of the degree not greater than $n-1$ in uniform metric, $Z_n(C)$ is the set of linear bounded operators that map $C$ to the subspace of trigonometric polynomials of degree not greater than $n-1$.","PeriodicalId":52827,"journal":{"name":"Researches in Mathematics","volume":null,"pages":null},"PeriodicalIF":0.0000,"publicationDate":"2021-10-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":"{\"title\":\"To the question of approximation of continuous periodic functions by trigonometric polynomials\",\"authors\":\"V. Shalaev\",\"doi\":\"10.15421/247711\",\"DOIUrl\":null,\"url\":null,\"abstract\":\"In the paper, it is proved that$$1 - \\\\frac{1}{2n} \\\\leqslant \\\\sup\\\\limits_{\\\\substack{f \\\\in C\\\\\\\\f \\\\ne const}} \\\\frac{E_n(f)_C}{\\\\omega_2(f; \\\\pi/n)_C} \\\\leqslant \\\\inf\\\\limits_{L_n \\\\in Z_n(C)} \\\\sup\\\\limits_{\\\\substack{f \\\\in C\\\\\\\\f \\\\ne const}} \\\\frac{\\\\| f - L_n(f) \\\\|_C}{\\\\omega_2 (f; \\\\pi/n)_C} \\\\leqslant 1$$where $\\\\omega_2(f; t)_C$ is the modulus of smoothness of the function $f \\\\in C$, $E_n(f)_C$ is the best approximation by trigonometric polynomials of the degree not greater than $n-1$ in uniform metric, $Z_n(C)$ is the set of linear bounded operators that map $C$ to the subspace of trigonometric polynomials of degree not greater than $n-1$.\",\"PeriodicalId\":52827,\"journal\":{\"name\":\"Researches in Mathematics\",\"volume\":null,\"pages\":null},\"PeriodicalIF\":0.0000,\"publicationDate\":\"2021-10-06\",\"publicationTypes\":\"Journal Article\",\"fieldsOfStudy\":null,\"isOpenAccess\":false,\"openAccessPdf\":\"\",\"citationCount\":\"0\",\"resultStr\":null,\"platform\":\"Semanticscholar\",\"paperid\":null,\"PeriodicalName\":\"Researches in Mathematics\",\"FirstCategoryId\":\"1085\",\"ListUrlMain\":\"https://doi.org/10.15421/247711\",\"RegionNum\":0,\"RegionCategory\":null,\"ArticlePicture\":[],\"TitleCN\":null,\"AbstractTextCN\":null,\"PMCID\":null,\"EPubDate\":\"\",\"PubModel\":\"\",\"JCR\":\"Q4\",\"JCRName\":\"Mathematics\",\"Score\":null,\"Total\":0}","platform":"Semanticscholar","paperid":null,"PeriodicalName":"Researches in Mathematics","FirstCategoryId":"1085","ListUrlMain":"https://doi.org/10.15421/247711","RegionNum":0,"RegionCategory":null,"ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q4","JCRName":"Mathematics","Score":null,"Total":0}
引用次数: 0

摘要

证明了$$1 - \frac{1}{2n} \leqslant \sup\limits_{\substack{f \in C\\f \ne const}} \frac{E_n(f)_C}{\omega_2(f; \pi/n)_C} \leqslant \inf\limits_{L_n \in Z_n(C)} \sup\limits_{\substack{f \in C\\f \ne const}} \frac{\| f - L_n(f) \|_C}{\omega_2 (f; \pi/n)_C} \leqslant 1$$其中$\omega_2(f; t)_C$是函数$f \in C$的光滑模,$E_n(f)_C$是一致度规中不大于$n-1$次的三角多项式的最佳逼近,$Z_n(C)$是将$C$映射到不大于$n-1$次的三角多项式的子空间的线性有界算子的集合。
本文章由计算机程序翻译,如有差异,请以英文原文为准。
查看原文
分享 分享
微信好友 朋友圈 QQ好友 复制链接
本刊更多论文
To the question of approximation of continuous periodic functions by trigonometric polynomials
In the paper, it is proved that$$1 - \frac{1}{2n} \leqslant \sup\limits_{\substack{f \in C\\f \ne const}} \frac{E_n(f)_C}{\omega_2(f; \pi/n)_C} \leqslant \inf\limits_{L_n \in Z_n(C)} \sup\limits_{\substack{f \in C\\f \ne const}} \frac{\| f - L_n(f) \|_C}{\omega_2 (f; \pi/n)_C} \leqslant 1$$where $\omega_2(f; t)_C$ is the modulus of smoothness of the function $f \in C$, $E_n(f)_C$ is the best approximation by trigonometric polynomials of the degree not greater than $n-1$ in uniform metric, $Z_n(C)$ is the set of linear bounded operators that map $C$ to the subspace of trigonometric polynomials of degree not greater than $n-1$.
求助全文
通过发布文献求助,成功后即可免费获取论文全文。 去求助
来源期刊
CiteScore
0.50
自引率
0.00%
发文量
8
审稿时长
16 weeks
期刊最新文献
On the analytic extension of three ratios of Horn's confluent hypergeometric function $\mathrm{H}_7$ Construction of a non-linear analytical model for the rotation parts building up process using regression analysis Automorphism groups of some non-nilpotent Leibniz algebras Some results on ultrametric 2-normed spaces Action of derivations on polynomials and on Jacobian derivations
×
引用
GB/T 7714-2015
复制
MLA
复制
APA
复制
导出至
BibTeX EndNote RefMan NoteFirst NoteExpress
×
×
提示
您的信息不完整,为了账户安全,请先补充。
现在去补充
×
提示
您因"违规操作"
具体请查看互助需知
我知道了
×
提示
现在去查看 取消
×
提示
确定
0
微信
客服QQ
Book学术公众号 扫码关注我们
反馈
×
意见反馈
请填写您的意见或建议
请填写您的手机或邮箱
已复制链接
已复制链接
快去分享给好友吧!
我知道了
×
扫码分享
扫码分享
Book学术官方微信
Book学术文献互助
Book学术文献互助群
群 号:481959085
Book学术
文献互助 智能选刊 最新文献 互助须知 联系我们:info@booksci.cn
Book学术提供免费学术资源搜索服务,方便国内外学者检索中英文文献。致力于提供最便捷和优质的服务体验。
Copyright © 2023 Book学术 All rights reserved.
ghs 京公网安备 11010802042870号 京ICP备2023020795号-1