Hongjia Chen, Teng Wang, Chun-Hua Zhang, Xiang Wang
{"title":"Solving the quadratic eigenvalue problem expressed in non-monomial bases by the tropical scaling","authors":"Hongjia Chen, Teng Wang, Chun-Hua Zhang, Xiang Wang","doi":"10.1007/s10444-024-10214-8","DOIUrl":"10.1007/s10444-024-10214-8","url":null,"abstract":"<div><p>In this paper, we consider the quadratic eigenvalue problem (QEP) expressed in various commonly used bases, including Taylor, Newton, and Lagrange bases. We propose to investigate the backward errors of the computed eigenpairs and condition numbers of eigenvalues for QEP solved by a class of block Kronecker linearizations. To improve the backward error and condition number of the QEP expressed in a non-monomial basis, we combine the tropical scaling with the block Kronecker linearization. We then establish upper bounds for the backward error of an approximate eigenpair of the QEP relative to the backward error of an approximate eigenpair of the block Kronecker linearization with and without tropical scaling. Moreover, we get bounds for the normwise condition number of an eigenvalue of the QEP relative to that of the block Kronecker linearization. Our investigation is accompanied by adequate numerical experiments to justify our theoretical findings.</p></div>","PeriodicalId":50869,"journal":{"name":"Advances in Computational Mathematics","volume":"50 6","pages":""},"PeriodicalIF":1.7,"publicationDate":"2024-12-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142760700","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Discontinuous Galerkin schemes for Stokes flow with Tresca boundary condition: iterative a posteriori error analysis","authors":"J.K. Djoko, T. Sayah","doi":"10.1007/s10444-024-10207-7","DOIUrl":"10.1007/s10444-024-10207-7","url":null,"abstract":"<div><p>In two dimensions, we propose and analyse an iterative <i>a posteriori</i> error indicator for the discontinuous Galerkin finite element approximations of the Stokes equations under boundary conditions of friction type. Two sources of error are identified here, namely; the discretisation error and the linearization error. Under a smallness assumption on data, we prove that the devised error estimator is reliable. Balancing these two errors is crucial to design an adaptive strategy for mesh refinement. We illustrate the theory with some representative numerical examples.</p></div>","PeriodicalId":50869,"journal":{"name":"Advances in Computational Mathematics","volume":"50 6","pages":""},"PeriodicalIF":1.7,"publicationDate":"2024-11-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s10444-024-10207-7.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142694785","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Helmholtz FEM solutions are locally quasi-optimal modulo low frequencies","authors":"M. Averseng, J. Galkowski, E. A. Spence","doi":"10.1007/s10444-024-10193-w","DOIUrl":"10.1007/s10444-024-10193-w","url":null,"abstract":"<div><p>For <i>h</i>-FEM discretisations of the Helmholtz equation with wavenumber <i>k</i>, we obtain <i>k</i>-explicit analogues of the classic local FEM error bounds of Nitsche and Schatz (Math. Comput. <b>28</b>(128), 937–958 1974), Wahlbin (1991, §9), Demlow et al.(Math. Comput. <b>80</b>(273), 1–9 2011), showing that these bounds hold with constants independent of <i>k</i>, provided one works in Sobolev norms weighted with <i>k</i> in the natural way. We prove two main results: (i) a bound on the local <span>(H^1)</span> error by the best approximation error plus the <span>(L^2)</span> error, both on a slightly larger set, and (ii) the bound in (i) but now with the <span>(L^2)</span> error replaced by the error in a negative Sobolev norm. The result (i) is valid for shape-regular triangulations, and is the <i>k</i>-explicit analogue of the main result of Demlow et al. (Math. Comput. <b>80</b>(273), 1–9 2011). The result (ii) is valid when the mesh is locally quasi-uniform on the scale of the wavelength (i.e., on the scale of <span>(k^{-1})</span>) and is the <i>k</i>-explicit analogue of the results of Nitsche and Schatz (Math. Comput. <b>28</b>(128), 937–958 1974), Wahlbin (1991, §9). Since our Sobolev spaces are weighted with <i>k</i> in the natural way, the result (ii) indicates that the Helmholtz FEM solution is locally quasi-optimal modulo low frequencies (i.e., frequencies <span>(lesssim k)</span>). Numerical experiments confirm this property, and also highlight interesting propagation phenomena in the Helmholtz FEM error.</p></div>","PeriodicalId":50869,"journal":{"name":"Advances in Computational Mathematics","volume":"50 6","pages":""},"PeriodicalIF":1.7,"publicationDate":"2024-11-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s10444-024-10193-w.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142664470","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Higher-order iterative decoupling for poroelasticity","authors":"Robert Altmann, Abdullah Mujahid, Benjamin Unger","doi":"10.1007/s10444-024-10200-0","DOIUrl":"10.1007/s10444-024-10200-0","url":null,"abstract":"<div><p>For the iterative decoupling of elliptic–parabolic problems such as poroelasticity, we introduce time discretization schemes up to order five based on the backward differentiation formulae. Its analysis combines techniques known from fixed-point iterations with the convergence analysis of the temporal discretization. As the main result, we show that the convergence depends on the interplay between the time step size and the parameters for the contraction of the iterative scheme. Moreover, this connection is quantified explicitly, which allows for balancing the single error components. Several numerical experiments illustrate and validate the theoretical results, including a three-dimensional example from biomechanics.</p></div>","PeriodicalId":50869,"journal":{"name":"Advances in Computational Mathematics","volume":"50 6","pages":""},"PeriodicalIF":1.7,"publicationDate":"2024-11-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s10444-024-10200-0.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142636743","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Stephan Dahlke, Marc Hovemann, Thorsten Raasch, Dorian Vogel
{"title":"Adaptive quarklet tree approximation","authors":"Stephan Dahlke, Marc Hovemann, Thorsten Raasch, Dorian Vogel","doi":"10.1007/s10444-024-10205-9","DOIUrl":"10.1007/s10444-024-10205-9","url":null,"abstract":"<div><p>This paper is concerned with near-optimal approximation of a given univariate function with elements of a polynomially enriched wavelet frame, a so-called quarklet frame. Inspired by <i>hp</i>-approximation techniques of Binev, we use the underlying tree structure of the frame elements to derive an adaptive algorithm that, under standard assumptions concerning the local errors, can be used to create approximations with an error close to the best tree approximation error for a given cardinality. We support our findings by numerical experiments demonstrating that this approach can be used to achieve inverse-exponential convergence rates.</p></div>","PeriodicalId":50869,"journal":{"name":"Advances in Computational Mathematics","volume":"50 6","pages":""},"PeriodicalIF":1.7,"publicationDate":"2024-10-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s10444-024-10205-9.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142555220","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Efficient computation of the sinc matrix function for the integration of second-order differential equations","authors":"Lidia Aceto, Fabio Durastante","doi":"10.1007/s10444-024-10202-y","DOIUrl":"10.1007/s10444-024-10202-y","url":null,"abstract":"<div><p>This work deals with the numerical solution of systems of oscillatory second-order differential equations which often arise from the semi-discretization in space of partial differential equations. Since these differential equations exhibit (pronounced or highly) oscillatory behavior, standard numerical methods are known to perform poorly. Our approach consists in directly discretizing the problem by means of Gautschi-type integrators based on sinc matrix functions. The novelty contained here is that of using a suitable rational approximation formula for the sinc matrix function to apply a rational Krylov-like approximation method with suitable choices of poles. In particular, we discuss the application of the whole strategy to a finite element discretization of the wave equation.</p></div>","PeriodicalId":50869,"journal":{"name":"Advances in Computational Mathematics","volume":"50 6","pages":""},"PeriodicalIF":1.7,"publicationDate":"2024-10-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142518925","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Sobolev regularity of bivariate isogeometric finite element spaces in case of a geometry map with degenerate corner","authors":"Ulrich Reif","doi":"10.1007/s10444-024-10203-x","DOIUrl":"10.1007/s10444-024-10203-x","url":null,"abstract":"<div><p>We investigate Sobolev regularity of bivariate functions obtained in Isogeometric Analysis when using geometry maps that are degenerate in the sense that the first partial derivatives vanish at isolated points. In particular, we show how the known <span>(C^1)</span>-conditions for D-patches have to be tightened to guarantee square integrability of second partial derivatives, as required when computing finite element approximations of elliptic fourth order PDEs like the biharmonic equation.</p></div>","PeriodicalId":50869,"journal":{"name":"Advances in Computational Mathematics","volume":"50 6","pages":""},"PeriodicalIF":1.7,"publicationDate":"2024-10-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s10444-024-10203-x.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142488419","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"An optimal ansatz space for moving least squares approximation on spheres","authors":"Ralf Hielscher, Tim Pöschl","doi":"10.1007/s10444-024-10201-z","DOIUrl":"10.1007/s10444-024-10201-z","url":null,"abstract":"<div><p>We revisit the moving least squares (MLS) approximation scheme on the sphere <span>(mathbb S^{d-1} subset {mathbb R}^d)</span>, where <span>(d>1)</span>. It is well known that using the spherical harmonics up to degree <span>(L in {mathbb N})</span> as ansatz space yields for functions in <span>(mathcal {C}^{L+1}(mathbb S^{d-1}))</span> the approximation order <span>(mathcal {O}left( h^{L+1} right) )</span>, where <i>h</i> denotes the fill distance of the sampling nodes. In this paper, we show that the dimension of the ansatz space can be almost halved, by including only spherical harmonics of even or odd degrees up to <i>L</i>, while preserving the same order of approximation. Numerical experiments indicate that using the reduced ansatz space is essential to ensure the numerical stability of the MLS approximation scheme as <span>(h rightarrow 0)</span>. Finally, we compare our approach with an MLS approximation scheme that uses polynomials on the tangent space of the sphere as ansatz space.</p></div>","PeriodicalId":50869,"journal":{"name":"Advances in Computational Mathematics","volume":"50 6","pages":""},"PeriodicalIF":1.7,"publicationDate":"2024-10-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s10444-024-10201-z.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142453126","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"A unified local projection-based stabilized virtual element method for the coupled Stokes-Darcy problem","authors":"Sudheer Mishra, E. Natarajan","doi":"10.1007/s10444-024-10199-4","DOIUrl":"10.1007/s10444-024-10199-4","url":null,"abstract":"<div><p>In this work, we propose and analyze a new stabilized virtual element method for the coupled Stokes-Darcy problem with Beavers-Joseph-Saffman interface condition on polygonal meshes. We derive two variants of local projection stabilization methods for the coupled Stokes-Darcy problem. The significance of local projection-based stabilization terms is that they provide reasonable control of the pressure component of the Stokes flow without involving higher-order derivative terms. The discrete inf-sup condition of the coupled Stokes-Darcy problem is established for the equal-order virtual element triplets involving velocity, hydraulic head, and pressure. The optimal error estimates are derived using the equal-order virtual elements in the energy and <span>(L^2)</span> norms. The proposed methods have several advantages: mass conservative, avoiding the coupling of the solution components, more accessible to implement, and performing efficiently on hybrid polygonal elements. Numerical experiments are conducted to depict the flexibility of the proposed methods, validating the theoretical results.</p></div>","PeriodicalId":50869,"journal":{"name":"Advances in Computational Mathematics","volume":"50 6","pages":""},"PeriodicalIF":1.7,"publicationDate":"2024-10-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142451931","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"A pressure-residual augmented GLS stabilized method for a type of Stokes equations with nonstandard boundary conditions","authors":"Huoyuan Duan, Roger C. E. Tan, Duowei Zhu","doi":"10.1007/s10444-024-10204-w","DOIUrl":"10.1007/s10444-024-10204-w","url":null,"abstract":"<div><p>With local pressure-residual stabilizations as an augmentation to the classical Galerkin/least-squares (GLS) stabilized method, a new locally evaluated residual-based stabilized finite element method is proposed for a type of Stokes equations from the incompressible flows. We focus on the study of a type of nonstandard boundary conditions involving the mixed tangential velocity and pressure Dirichlet boundary conditions. Unexpectedly, in sharp contrast to the standard no-slip velocity Dirichlet boundary condition, neither the discrete LBB inf-sup stable elements nor the stabilized methods such as the classical GLS method could certainly ensure a convergent finite element solution, because the velocity solution could be very weak with its gradient not being square integrable. The main purpose of this paper is to study the error estimates of the new stabilized method for approximating the very weak velocity solution; with the local pressure-residual stabilizations, we can manage to prove the error estimates with a reasonable convergence order. Numerical results are provided to illustrate the performance and the theoretical results of the proposed method.</p></div>","PeriodicalId":50869,"journal":{"name":"Advances in Computational Mathematics","volume":"50 5","pages":""},"PeriodicalIF":1.7,"publicationDate":"2024-10-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142431043","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}