CalcoloPub Date : 2025-01-01Epub Date: 2024-12-28DOI: 10.1007/s10092-024-00627-8
Nis-Erik Bohne, Benedikt Gräßle, Stefan A Sauter
{"title":"Pressure-improved Scott-Vogelius type elements.","authors":"Nis-Erik Bohne, Benedikt Gräßle, Stefan A Sauter","doi":"10.1007/s10092-024-00627-8","DOIUrl":"https://doi.org/10.1007/s10092-024-00627-8","url":null,"abstract":"<p><p>The Scott-Vogelius element is a popular finite element for the discretization of the Stokes equations which enjoys inf-sup stability and gives divergence-free velocity approximations. However, it is well known that the convergence rates for the discrete pressure deteriorate in the presence of certain <i>critical vertices</i> in a triangulation of the domain. Modifications of the Scott-Vogelius element such as the recently introduced pressure-wired Stokes element also suffer from this effect. In this paper we introduce a simple modification strategy for these pressure spaces that preserves the inf-sup stability while the pressure converges at an optimal rate.</p>","PeriodicalId":9522,"journal":{"name":"Calcolo","volume":"62 1","pages":"8"},"PeriodicalIF":1.4,"publicationDate":"2025-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11682022/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142906642","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}
CalcoloPub Date : 2025-01-01Epub Date: 2025-07-25DOI: 10.1007/s10092-025-00654-z
Haoze He, Daniel Kressner
{"title":"A simple, randomized algorithm for diagonalizing normal matrices.","authors":"Haoze He, Daniel Kressner","doi":"10.1007/s10092-025-00654-z","DOIUrl":"10.1007/s10092-025-00654-z","url":null,"abstract":"<p><p>We present and analyze a simple numerical method that diagonalizes a complex normal matrix <i>A</i> by diagonalizing the Hermitian matrix obtained from a random linear combination of the Hermitian and skew-Hermitian parts of <i>A</i>.</p>","PeriodicalId":9522,"journal":{"name":"Calcolo","volume":"62 3","pages":"30"},"PeriodicalIF":1.3,"publicationDate":"2025-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12296832/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144728113","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}
CalcoloPub Date : 2024-09-16DOI: 10.1007/s10092-024-00611-2
Fangyuan Wang, Qiming Wang, Zhaojie Zhou
{"title":"Adaptive finite element approximation of bilinear optimal control problem with fractional Laplacian","authors":"Fangyuan Wang, Qiming Wang, Zhaojie Zhou","doi":"10.1007/s10092-024-00611-2","DOIUrl":"https://doi.org/10.1007/s10092-024-00611-2","url":null,"abstract":"<p>We investigate the application of a posteriori error estimate to a fractional optimal control problem with pointwise control constraints. Specifically, we address a problem in which the state equation is formulated as an integral form of the fractional Laplacian equation, with the control variable embedded within the state equation as a coefficient. We propose two distinct finite element discretization approaches for an optimal control problem. The first approach employs a fully discrete scheme where the control variable is discretized using piecewise constant functions. The second approach, a semi-discrete scheme, does not discretize the control variable. Using the first-order optimality condition, the second-order optimality condition, and a solution regularity analysis for the optimal control problem, we devise a posteriori error estimates. Based on the established error estimates framework, an adaptive refinement strategy is developed to help achieve the optimal convergence rate. Numerical experiments are given to illustrate the theoretical findings.</p>","PeriodicalId":9522,"journal":{"name":"Calcolo","volume":"4 1","pages":""},"PeriodicalIF":1.7,"publicationDate":"2024-09-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142260832","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}
CalcoloPub Date : 2024-09-16DOI: 10.1007/s10092-024-00614-z
Shan Li, Cunxuan Du, Zhongqing Wang
{"title":"An explicit two-grid spectral deferred correction method for nonlinear fractional pantograph differential equations","authors":"Shan Li, Cunxuan Du, Zhongqing Wang","doi":"10.1007/s10092-024-00614-z","DOIUrl":"https://doi.org/10.1007/s10092-024-00614-z","url":null,"abstract":"<p>In this paper, we propose an explicit two-grid spectral deferred correction method for solving the nonlinear fractional pantograph differential equations. We design a partition including the global and local grids, which reduces the interaction between the subintervals caused by the delay term. We also analyze the numerical errors of the suggested approach for the prediction step and the correction step, respectively. Numerical experiments confirm the theoretical expectations.</p>","PeriodicalId":9522,"journal":{"name":"Calcolo","volume":"2 1","pages":""},"PeriodicalIF":1.7,"publicationDate":"2024-09-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142260833","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}
CalcoloPub Date : 2024-09-13DOI: 10.1007/s10092-024-00589-x
Rashad M. Asharabi, Mustafa Q. Khirallah
{"title":"A modification of the periodic nonuniform sampling involving derivatives with a Gaussian multiplier","authors":"Rashad M. Asharabi, Mustafa Q. Khirallah","doi":"10.1007/s10092-024-00589-x","DOIUrl":"https://doi.org/10.1007/s10092-024-00589-x","url":null,"abstract":"<p>The periodic nonuniform sampling series, involving periodic samples of both the function and its first <i>r</i> derivatives, was initially introduced by Nathan (Inform Control 22: 172–182, 1973). Since then, various authors have extended this sampling series in different contexts over the past decades. However, the application of the periodic nonuniform derivative sampling series in approximation theory has been limited due to its slow convergence. In this article, we introduce a modification to the periodic nonuniform sampling involving derivatives by incorporating a Gaussian multiplier. This modification results in a significantly improved convergence rate, which now follows an exponential order. This is a significant improvement compared to the original series, which had a convergence rate of <span>(O(N^{-1/p}))</span> where <span>(p>1)</span>. The introduced modification relies on a complex-analytic technique and is applicable to a wide range of functions. Specifically, it is suitable for the class of entire functions of exponential type that satisfy a decay condition, as well as for the class of analytic functions defined on a horizontal strip. To validate the presented theoretical analysis, the paper includes rigorous numerical experiments.</p>","PeriodicalId":9522,"journal":{"name":"Calcolo","volume":"25 1","pages":""},"PeriodicalIF":1.7,"publicationDate":"2024-09-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142260835","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}
CalcoloPub Date : 2024-09-10DOI: 10.1007/s10092-024-00613-0
Michael S. Floater
{"title":"On the positivity of B-spline Wronskians","authors":"Michael S. Floater","doi":"10.1007/s10092-024-00613-0","DOIUrl":"https://doi.org/10.1007/s10092-024-00613-0","url":null,"abstract":"<p>A proof that Wronskians of non-zero B-splines are positive is given, using only recursive formulas for B-splines and their derivatives. This could be used to generalize the de Boor–DeVore geometric proof of the Schoenberg–Whitney conditions and total positivity of B-splines to Hermite interpolation. For Wronskians of maximal order with respect to a given degree, positivity follows from a simple formula.</p>","PeriodicalId":9522,"journal":{"name":"Calcolo","volume":"4 1","pages":""},"PeriodicalIF":1.7,"publicationDate":"2024-09-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142217802","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}
CalcoloPub Date : 2024-08-31DOI: 10.1007/s10092-024-00606-z
Ruishu Liu, Xiaojie Wang, Lei Dai
{"title":"An unconditional boundary and dynamics preserving scheme for the stochastic epidemic model","authors":"Ruishu Liu, Xiaojie Wang, Lei Dai","doi":"10.1007/s10092-024-00606-z","DOIUrl":"https://doi.org/10.1007/s10092-024-00606-z","url":null,"abstract":"<p>In the present article, we construct a logarithm transformation based Milstein-type method for the stochastic susceptible-infected-susceptible (SIS) epidemic model evolving in the domain (0, <i>N</i>). The new scheme is explicit and unconditionally boundary and dynamics preserving, when used to solve the stochastic SIS epidemic model. Also, it is proved that the scheme has a strong convergence rate of order one. Different from existing time discretization schemes, the newly proposed scheme for any time step size <span>(h>0)</span>, not only produces numerical approximations living in the entire domain (0, <i>N</i>), but also unconditionally reproduces the extinction and persistence behavior of the original model, with no additional requirements imposed on the model parameters. Numerical experiments are presented to verify our theoretical findings.</p>","PeriodicalId":9522,"journal":{"name":"Calcolo","volume":"13 1","pages":""},"PeriodicalIF":1.7,"publicationDate":"2024-08-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142227055","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}
CalcoloPub Date : 2024-08-24DOI: 10.1007/s10092-024-00609-w
Ajay Singh Rathore, Vembu Shanthi
{"title":"A computational method for singularly perturbed reaction–diffusion type system of integro-differential equations with discontinuous source term","authors":"Ajay Singh Rathore, Vembu Shanthi","doi":"10.1007/s10092-024-00609-w","DOIUrl":"https://doi.org/10.1007/s10092-024-00609-w","url":null,"abstract":"<p>This paper provides a qualitative and quantitative study of a second-order Singularly Perturbed Reaction–Diffusion type System of Integro-differential equations with discontinuous source term. To obtain the numerical solution of the problem, an exponentially-fitted method that can be applied to a Shishkin mesh. This method shows that uniform convergence with respect to the perturbation parameter and necessary examples are given.</p>","PeriodicalId":9522,"journal":{"name":"Calcolo","volume":"75 2 1","pages":""},"PeriodicalIF":1.7,"publicationDate":"2024-08-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142217803","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}
CalcoloPub Date : 2024-08-21DOI: 10.1007/s10092-024-00596-y
Hamza Ennaji, Yvain Quéau, Abderrahim Elmoataz
{"title":"A primal-dual algorithm for computing Finsler distances and applications","authors":"Hamza Ennaji, Yvain Quéau, Abderrahim Elmoataz","doi":"10.1007/s10092-024-00596-y","DOIUrl":"https://doi.org/10.1007/s10092-024-00596-y","url":null,"abstract":"<p>This note discusses the computation of the distance function with respect to Finsler metrics. To this end, we show how the Finsler variants of the Eikonal equation can be solved by a primal-dual algorithm exploiting the variational structure. We also discuss the acceleration of the algorithm by preconditioning techniques, and illustrate the flexibility of the proposed method through a series of numerical examples.</p>","PeriodicalId":9522,"journal":{"name":"Calcolo","volume":"422 1","pages":""},"PeriodicalIF":1.7,"publicationDate":"2024-08-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142217804","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}
CalcoloPub Date : 2024-08-08DOI: 10.1007/s10092-024-00597-x
Sangeeta Yadav, Sashikumaar Ganesan
{"title":"ConvStabNet: a CNN-based approach for the prediction of local stabilization parameter for SUPG scheme","authors":"Sangeeta Yadav, Sashikumaar Ganesan","doi":"10.1007/s10092-024-00597-x","DOIUrl":"https://doi.org/10.1007/s10092-024-00597-x","url":null,"abstract":"<p>This paper presents ConvStabNet, a convolutional neural network designed to predict optimal stabilization parameters for each cell in the Streamline Upwind Petrov Galerkin (SUPG) stabilization scheme. ConvStabNet employs a shared parameter approach, allowing the network to understand the relationships between cell characteristics and their corresponding stabilization parameters while efficiently handling the parameter space. Comparative analyses with state-of-the-art neural network solvers based on variational formulations highlight the superior performance of ConvStabNet. To improve the accuracy of SUPG in solving partial differential equations (PDEs) with interior and boundary layers, ConvStabNet incorporates a loss function that combines a strong residual component with a cross-wind derivative term. The findings confirm ConvStabNet as a promising method for accurately predicting stabilization parameters in SUPG, thereby marking it as an advancement over neural network-based PDE solvers.</p>","PeriodicalId":9522,"journal":{"name":"Calcolo","volume":"41 1","pages":""},"PeriodicalIF":1.7,"publicationDate":"2024-08-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141943635","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}