{"title":"Shape-preserving subdivision scheme with the third-order accuracy and C2 smoothness","authors":"Yejin Kim , Hyoseon Yang , Jungho Yoon","doi":"10.1016/j.matcom.2025.03.030","DOIUrl":"10.1016/j.matcom.2025.03.030","url":null,"abstract":"<div><div>In this study, we present a novel shape preserving <span><math><msup><mrow><mi>C</mi></mrow><mrow><mn>2</mn></mrow></msup></math></span> subdivision scheme with third-order accuracy. Its limit functions preserve both monotonicity and convexity of the given data, even in cases where the data are non-strictly monotone or convex. To achieve this, we especially devise a modified <em>minmod</em> method, originally introduced in Gelb and Tadmor (2006) to detect edges from a piecewise smooth data, that plays a role of limiting procedure to prevent spurious oscillations. While most of shape preserving schemes are complicated, the proposed method is conceptually simple to implement. Some numerical results are presented to demonstrate the accuracy, smoothness and shape preserving performance of the proposed scheme.</div></div>","PeriodicalId":49856,"journal":{"name":"Mathematics and Computers in Simulation","volume":"235 ","pages":"Pages 160-174"},"PeriodicalIF":4.4,"publicationDate":"2025-04-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143785543","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Alexander I. Bufetov, Juan Marshall-Maldonado, Boris Solomyak
{"title":"Local spectral estimates and quantitative weak mixing for substitution \u0000 \u0000 Z\u0000 ${mathbb {Z}}$\u0000 -actions","authors":"Alexander I. Bufetov, Juan Marshall-Maldonado, Boris Solomyak","doi":"10.1112/jlms.70136","DOIUrl":"https://doi.org/10.1112/jlms.70136","url":null,"abstract":"<p>The paper investigates Hölder and log-Hölder regularity of spectral measures for weakly mixing substitutions and the related question of quantitative weak mixing. It is assumed that the substitution is primitive, aperiodic, and its substitution matrix is irreducible over the rationals. In the case when there are no eigenvalues of the substitution matrix on the unit circle, Theorem 2.2 says that a weakly mixing substitution <span></span><math>\u0000 <semantics>\u0000 <mi>Z</mi>\u0000 <annotation>${mathbb {Z}}$</annotation>\u0000 </semantics></math>-action has uniformly log-Hölder regular spectral measures, and hence admits power-logarithmic bounds for the rate of weak mixing. In the more delicate Salem substitution case, Theorem 2.5 says that Hölder regularity holds for spectral parameters from the respective number field, but the Hölder exponent cannot be chosen uniformly.</p>","PeriodicalId":49989,"journal":{"name":"Journal of the London Mathematical Society-Second Series","volume":"111 4","pages":""},"PeriodicalIF":1.0,"publicationDate":"2025-04-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1112/jlms.70136","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143770171","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}