{"title":"Convergence analysis of three semidiscrete numerical schemes for nonlocal geometric flows including perimeter terms","authors":"Wei Jiang, Chunmei Su, Ganghui Zhang","doi":"10.1093/imanum/draf015","DOIUrl":"https://doi.org/10.1093/imanum/draf015","url":null,"abstract":"We present and analyze three distinct semidiscrete schemes for solving nonlocal geometric flows incorporating perimeter terms. These schemes are based on the finite difference method, the finite element method and the finite element method with a specific tangential motion. We offer rigorous proofs of quadratic convergence under $H^{1}$-norm for the first scheme and linear convergence under $H^{1}$-norm for the latter two schemes. All error estimates rely on the observation that the error of the nonlocal term can be controlled by the error of the local term. Furthermore, we explore the relationship between the convergence under $L^infty $-norm and manifold distance. Extensive numerical experiments are conducted to verify the convergence analysis, and demonstrate the accuracy of our schemes under various norms for different types of nonlocal flows.","PeriodicalId":56295,"journal":{"name":"IMA Journal of Numerical Analysis","volume":"52 1","pages":""},"PeriodicalIF":2.1,"publicationDate":"2025-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143893397","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}
{"title":"A backward differential deep learning-based algorithm for solving high-dimensional nonlinear backward stochastic differential equations","authors":"Lorenc Kapllani, Long Teng","doi":"10.1093/imanum/draf022","DOIUrl":"https://doi.org/10.1093/imanum/draf022","url":null,"abstract":"In this work we propose a novel backward differential deep learning-based algorithm for solving high-dimensional nonlinear backward stochastic differential equations (BSDEs), where the deep neural network (DNN) models are trained, not only on the inputs and labels, but also on the differentials of the corresponding labels. This is motivated by the fact that differential deep learning can provide an efficient approximation of the labels and their derivatives with respect to inputs. The BSDEs are reformulated as differential deep learning problems by using Malliavin calculus. The Malliavin derivatives of the BSDE solution themselves satisfy another BSDE, resulting thus in a system of BSDEs. Such formulation requires the estimation of the solution, its gradient and the Hessian matrix, represented by the triple of processes $left (Y, Z, varGamma right ).$ All the integrals within this system are discretized by using the Euler–Maruyama method. Subsequently, DNNs are employed to approximate the triple of these unknown processes. The DNN parameters are backwardly optimized at each time step by minimizing a differential learning type loss function, which is defined as a weighted sum of the dynamics of the discretized BSDE system, with the first term providing the dynamics of the process $Y$ and the other the process $Z$. An error analysis is carried out to show the convergence of the proposed algorithm. Various numerical experiments of up to $50$ dimensions are provided to demonstrate the high efficiency. Both theoretically and numerically, it is demonstrated that our proposed scheme is more efficient in terms of computation time or accuracy compared with other contemporary deep learning-based methodologies.","PeriodicalId":56295,"journal":{"name":"IMA Journal of Numerical Analysis","volume":"39 1","pages":""},"PeriodicalIF":2.1,"publicationDate":"2025-04-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143884791","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}
{"title":"An asymptotic preserving scheme for the defocusing Davey–Stewartson II equation in the semiclassical limit","authors":"Dandan Wang, Hanquan Wang","doi":"10.1093/imanum/draf019","DOIUrl":"https://doi.org/10.1093/imanum/draf019","url":null,"abstract":"This article is devoted to constructing an asymptotic preserving method for the defocusing Davey–Stewartson II equation in the semiclassical limit. First, we introduce the Wentzel–Kramers–Brillouin ansatz $varPsi =A^varepsilon e^{iphi ^varepsilon /varepsilon }$ for the equation and obtain the new system for both $A^varepsilon $ and $phi ^varepsilon $, where the complex-valued amplitude function $A^varepsilon $ can avoid automatically the singularity of the quantum potential in vacuum. Secondly, we prove the local existence of the solutions of the new system for $tin [0,T]$, and show that the solutions of the new system are convergent to the limit when $varepsilon rightarrow 0$. Finally, we construct a second-order time-splitting Fourier spectral method for the new system and numerous numerical experiments show that the method is uniformly accurate with respect to $varepsilon $, i.e., its accuracy does not deteriorate for vanishing $varepsilon $, and it is an asymptotic preserving one. However, it might not be uniformly convergent.","PeriodicalId":56295,"journal":{"name":"IMA Journal of Numerical Analysis","volume":"79 1","pages":""},"PeriodicalIF":2.1,"publicationDate":"2025-04-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143878130","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}
{"title":"Spatio-temporal Lie–Poisson discretization for incompressible magnetohydrodynamics on the sphere","authors":"Klas Modin, Michael Roop","doi":"10.1093/imanum/draf024","DOIUrl":"https://doi.org/10.1093/imanum/draf024","url":null,"abstract":"We give a structure preserving spatio-temporal discretization for incompressible magnetohydrodynamics (MHD) on the sphere. Discretization in space is based on the theory of geometric quantization, which yields a spatially discretized analogue of the MHD equations as a finite-dimensional Lie–Poisson system on the dual of the magnetic extension Lie algebra $mathfrak{f}=mathfrak{su}(N)ltimes mathfrak{su}(N)^{*}$. We also give accompanying structure preserving time discretizations for Lie–Poisson systems on the dual of semidirect product Lie algebras of the form $mathfrak{f}=mathfrak{g}ltimes mathfrak{g^{*}}$, where $mathfrak{g}$ is a $J$-quadratic Lie algebra. The time integration method is free of computationally costly matrix exponentials. We prove that the full method preserves a modified Lie–Poisson structure and corresponding Casimir functions, and that the modified structure and Casimirs converge to the continuous ones. The method is demonstrated for two models of magnetic fluids: incompressible MHD and Hazeltine’s model.","PeriodicalId":56295,"journal":{"name":"IMA Journal of Numerical Analysis","volume":"26 1","pages":""},"PeriodicalIF":2.1,"publicationDate":"2025-04-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143878131","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}
{"title":"On the approximation of singular functions by series of noninteger powers","authors":"Mohan Zhao, Kirill Serkh","doi":"10.1093/imanum/draf006","DOIUrl":"https://doi.org/10.1093/imanum/draf006","url":null,"abstract":"In this paper, we describe an algorithm for approximating functions of the form $f(x)=int _{a}^{b} x^{mu } sigma (mu ) , {text{d}} mu $ over $[0,1]$, where $sigma (mu )$ is some signed Radon measure, or, more generally, of the form $f(x) = {{langle sigma (mu ), x^mu rangle }}$, where $sigma (mu )$ is some distribution supported on $[a,b]$, with $0 <a < b< infty $. One example from this class of functions is $x^{c} (log{x})^{m}=(-1)^{m} {{langle delta ^{(m)}(mu -c), x^mu rangle }}$, where $aleq c leq b$ and $m geq 0$ is an integer. Given the desired accuracy $varepsilon $ and the values of $a$ and $b$, our method determines a priori a collection of noninteger powers $t_{1}$, $t_{2}$, …, $t_{N}$, so that the functions are approximated by series of the form $f(x)approx sum _{j=1}^{N} c_{j} x^{t_{j}}$, and a set of collocation points $x_{1}$, $x_{2}$, …, $x_{N}$, such that the expansion coefficients can be found by collocating the function at these points. We prove that our method has a small uniform approximation error, which is proportional to $varepsilon $ multiplied by some small constants, and that the number of singular powers and collocation points grows as $N=O(log{frac{1}{varepsilon }})$. We demonstrate the performance of our algorithm with several numerical experiments.","PeriodicalId":56295,"journal":{"name":"IMA Journal of Numerical Analysis","volume":"32 1","pages":""},"PeriodicalIF":2.1,"publicationDate":"2025-04-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143878121","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}
{"title":"Optimal convergence rates of an adaptive hybrid FEM-BEM method for full-space linear transmission problems","authors":"Gregor Gantner, Michele Ruggeri","doi":"10.1093/imanum/draf023","DOIUrl":"https://doi.org/10.1093/imanum/draf023","url":null,"abstract":"We consider a hybrid FEM-BEM method to compute approximations of full-space linear elliptic transmission problems. First, we derive a priori and a posteriori error estimates. Then, building on the latter, we present an adaptive algorithm and prove that it converges at optimal rates with respect to the number of mesh elements. Finally, we provide numerical experiments, demonstrating the practical performance of the adaptive algorithm.","PeriodicalId":56295,"journal":{"name":"IMA Journal of Numerical Analysis","volume":"13 1","pages":""},"PeriodicalIF":2.1,"publicationDate":"2025-04-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143875731","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}
{"title":"Space-time hybridizable discontinuous Galerkin method for advection-diffusion: the advection-dominated regime","authors":"Yuan Wang, Sander Rhebergen","doi":"10.1093/imanum/draf013","DOIUrl":"https://doi.org/10.1093/imanum/draf013","url":null,"abstract":"We analyze a space-time hybridizable discontinuous Galerkin method to solve the time-dependent advection-diffusion equation. We prove stability of the discretization in the advection-dominated regime by using weighted test functions and derive a priori space-time error estimates. Numerical examples illustrate the theoretical results.","PeriodicalId":56295,"journal":{"name":"IMA Journal of Numerical Analysis","volume":"31 1","pages":""},"PeriodicalIF":2.1,"publicationDate":"2025-04-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143866498","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}
{"title":"A hybridizable discontinuous Galerkin method for Stokes/Darcy coupling on dissimilar meshes","authors":"Isaac Bermúdez, Jaime Manríquez, Manuel Solano","doi":"10.1093/imanum/drae109","DOIUrl":"https://doi.org/10.1093/imanum/drae109","url":null,"abstract":"We present and analyze a hybridizable discontinuous Galerkin method for coupling Stokes and Darcy equations, whose domains are discretized by two independent triangulations. This causes nonconformity at the intersection of the subdomains or leaves a gap (unmeshed region) between them. In order to properly couple the two different discretizations and obtain a high-order scheme, we propose suitable transmission conditions based on mass conservation, equilibrium of normal forces and the Beavers–Joseph–Saffman law. Since the meshes do not necessarily coincide, we use the Transfer Path Method to tie them. We establish the well-posedness of the method and provide error estimates where the influences of the nonconformity and the gap are explicit in the constants. Finally, numerical experiments that illustrate the performance of the method are shown.","PeriodicalId":56295,"journal":{"name":"IMA Journal of Numerical Analysis","volume":"45 1","pages":""},"PeriodicalIF":2.1,"publicationDate":"2025-04-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143851018","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}
{"title":"A priori error estimates for optimal control problems governed by the transient Stokes equations and subject to state constraints pointwise in time","authors":"Dmitriy Leykekhman, Boris Vexler, Jakob Wagner","doi":"10.1093/imanum/draf018","DOIUrl":"https://doi.org/10.1093/imanum/draf018","url":null,"abstract":"In this paper, we consider a state constrained optimal control problem governed by the transient Stokes equations. The state constraint is given by an $L^{2}$ functional in space, which is required to fulfill a pointwise bound in time. The discretization scheme for the Stokes equations consists of inf-sup stable finite elements in space and a discontinuous Galerkin method in time, for which we have recently established best approximation type error estimates. Using these error estimates, for the discrete control problem we derive error estimates and as a by-product we show an improved regularity for the optimal control. We complement our theoretical analysis with numerical results.","PeriodicalId":56295,"journal":{"name":"IMA Journal of Numerical Analysis","volume":"21 1","pages":""},"PeriodicalIF":2.1,"publicationDate":"2025-04-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143824844","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}
{"title":"Numerical methods and regularity properties for viscosity solutions of nonlocal in space and time diffusion equations","authors":"Félix del Teso, Łukasz Płociniczak","doi":"10.1093/imanum/draf011","DOIUrl":"https://doi.org/10.1093/imanum/draf011","url":null,"abstract":"We consider a general family of nonlocal in space and time diffusion equations with space-time dependent diffusivity and prove convergence of finite difference schemes in the context of viscosity solutions under very mild conditions. The proofs, based on regularity properties and compactness arguments on the numerical solution, allow to inherit a number of interesting results for the limit equation. More precisely, assuming Hölder regularity only on the initial condition, we prove convergence of the scheme, space-time Hölder regularity of the solution, depending on the fractional orders of the operators, as well as specific blow up rates of the first time derivative. The schemes’ performance is further numerically verified using both constructed exact solutions and realistic examples. Our experiments show that multithreaded implementation yields an efficient method to solve nonlocal equations numerically.","PeriodicalId":56295,"journal":{"name":"IMA Journal of Numerical Analysis","volume":"30 1","pages":""},"PeriodicalIF":2.1,"publicationDate":"2025-04-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143813720","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}