{"title":"The Existence the Solution of Nonlinear Discrete Schemes and Convergence of a Linearized Iterative Method for time-dependent PNP Equations","authors":"Yang Liu, Shi Shu, Ying Yang","doi":"arxiv-2312.00291","DOIUrl":"https://doi.org/arxiv-2312.00291","url":null,"abstract":"We establish the existence theory of several commonly used finite element\u0000(FE) nonlinear fully discrete solutions, and the convergence theory of a\u0000linearized iteration. First, it is shown for standard FE, SUPG and\u0000edge-averaged method respectively that the stiffness matrix is a column\u0000M-matrix under certain conditions, and then the existence theory of these three\u0000FE nonlinear fully discrete solutions is presented by using Brouwer's fixed\u0000point theorem. Second, the contraction of a commonly used linearized iterative\u0000method-Gummel iteration is proven, and then the convergence theory is\u0000established for the iteration. At last, a numerical experiment is shown to\u0000verifies the theories.","PeriodicalId":501061,"journal":{"name":"arXiv - CS - Numerical Analysis","volume":"40 6","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138503951","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Approximation Bounds for Model Reduction on Polynomially Mapped Manifolds","authors":"Patrick Buchfink, Silke Glas, Bernard Haasdonk","doi":"arxiv-2312.00724","DOIUrl":"https://doi.org/arxiv-2312.00724","url":null,"abstract":"For projection-based linear-subspace model order reduction (MOR), it is well\u0000known that the Kolmogorov n-width describes the best-possible error for a\u0000reduced order model (ROM) of size n. In this paper, we provide approximation\u0000bounds for ROMs on polynomially mapped manifolds. In particular, we show that\u0000the approximation bounds depend on the polynomial degree p of the mapping\u0000function as well as on the linear Kolmogorov n-width for the underlying\u0000problem. This results in a Kolmogorov (n, p)-width, which describes a lower\u0000bound for the best-possible error for a ROM on polynomially mapped manifolds of\u0000polynomial degree p and reduced size n.","PeriodicalId":501061,"journal":{"name":"arXiv - CS - Numerical Analysis","volume":"39 9","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138503959","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Andrii Dmytryshyn, Froilán Dopico, Paul Van Dooren
{"title":"Minimal rank factorizations of polynomial matrices","authors":"Andrii Dmytryshyn, Froilán Dopico, Paul Van Dooren","doi":"arxiv-2312.00676","DOIUrl":"https://doi.org/arxiv-2312.00676","url":null,"abstract":"We investigate rank revealing factorizations of rank deficient $m times n$\u0000polynomial matrices $P(lambda)$ into products of three, $P(lambda) =\u0000L(lambda) E(lambda) R(lambda)$, or two, $P(lambda) = L(lambda)\u0000R(lambda)$, polynomial matrices. Among all possible factorizations of these\u0000types, we focus on those for which $L(lambda)$ and/or $R(lambda)$ is a\u0000minimal basis, since they allow us to relate easily the degree of $P(lambda)$\u0000with some degree properties of the factors. We call these factorizations\u0000minimal rank factorizations. Motivated by the well-known fact that,\u0000generically, rank deficient polynomial matrices over the complex field do not\u0000have eigenvalues, we pay particular attention to the properties of the minimal\u0000rank factorizations of polynomial matrices without eigenvalues. We carefully\u0000analyze the degree properties of generic minimal rank factorizations in the set\u0000of complex $m times n$ polynomial matrices with normal rank at most $r$ and\u0000degree at most $d$, and we prove that they are of the form $L(lambda)\u0000R(lambda)$, where the degrees of the $r$ columns of $L(lambda)$ differ at\u0000most by one, the degrees of the $r$ rows of $R(lambda)$ differ at most by one,\u0000and, for each $i=1, ldots, r$, the sum of the degrees of the $i$th column of\u0000$L(lambda)$ and of the $i$th row of $R(lambda)$ is equal to $d$. Finally, we\u0000show how these sets of polynomial matrices with generic factorizations are\u0000related to the sets of polynomial matrices with generic eigenstructures.","PeriodicalId":501061,"journal":{"name":"arXiv - CS - Numerical Analysis","volume":" 27","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138494187","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Alejandro N. Diaz, Youngsoo Choi, Matthias Heinkenschloss
{"title":"Nonlinear-manifold reduced order models with domain decomposition","authors":"Alejandro N. Diaz, Youngsoo Choi, Matthias Heinkenschloss","doi":"arxiv-2312.00713","DOIUrl":"https://doi.org/arxiv-2312.00713","url":null,"abstract":"A nonlinear-manifold reduced order model (NM-ROM) is a great way of\u0000incorporating underlying physics principles into a neural network-based\u0000data-driven approach. We combine NM-ROMs with domain decomposition (DD) for\u0000efficient computation. NM-ROMs offer benefits over linear-subspace ROMs\u0000(LS-ROMs) but can be costly to train due to parameter scaling with the\u0000full-order model (FOM) size. To address this, we employ DD on the FOM, compute\u0000subdomain NM-ROMs, and then merge them into a global NM-ROM. This approach has\u0000multiple advantages: parallel training of subdomain NM-ROMs, fewer parameters\u0000than global NM-ROMs, and adaptability to subdomain-specific FOM features. Each\u0000subdomain NM-ROM uses a shallow, sparse autoencoder, enabling hyper-reduction\u0000(HR) for improved computational speed. In this paper, we detail an algebraic DD\u0000formulation for the FOM, train HR-equipped NM-ROMs for subdomains, and\u0000numerically compare them to DD LS-ROMs with HR. Results show a significant\u0000accuracy boost, on the order of magnitude, for the proposed DD NM-ROMs over DD\u0000LS-ROMs in solving the 2D steady-state Burgers' equation.","PeriodicalId":501061,"journal":{"name":"arXiv - CS - Numerical Analysis","volume":"39 10","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138503958","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"A Preconditioned Interior Point Method for Support Vector Machines Using an ANOVA-Decomposition and NFFT-Based Matrix-Vector Products","authors":"Theresa Wagner, John W. Pearson, Martin Stoll","doi":"arxiv-2312.00538","DOIUrl":"https://doi.org/arxiv-2312.00538","url":null,"abstract":"In this paper we consider the numerical solution to the soft-margin support\u0000vector machine optimization problem. This problem is typically solved using the\u0000SMO algorithm, given the high computational complexity of traditional\u0000optimization algorithms when dealing with large-scale kernel matrices. In this\u0000work, we propose employing an NFFT-accelerated matrix-vector product using an\u0000ANOVA decomposition for the feature space that is used within an interior point\u0000method for the overall optimization problem. As this method requires the\u0000solution of a linear system of saddle point form we suggest a preconditioning\u0000approach that is based on low-rank approximations of the kernel matrix together\u0000with a Krylov subspace solver. We compare the accuracy of the ANOVA-based\u0000kernel with the default LIBSVM implementation. We investigate the performance\u0000of the different preconditioners as well as the accuracy of the ANOVA kernel on\u0000several large-scale datasets.","PeriodicalId":501061,"journal":{"name":"arXiv - CS - Numerical Analysis","volume":"121 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138517342","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Tsung-Ming Huang, Yueh-Cheng Kuo, Ren-Cang Li, Wen-Wei Lin
{"title":"On Novel Fixed-Point-Type Iterations with Structure-Preserving Doubling Algorithms for Stochastic Continuous-time Algebraic Riccati equations","authors":"Tsung-Ming Huang, Yueh-Cheng Kuo, Ren-Cang Li, Wen-Wei Lin","doi":"arxiv-2312.00328","DOIUrl":"https://doi.org/arxiv-2312.00328","url":null,"abstract":"In this paper we mainly propose efficient and reliable numerical algorithms\u0000for solving stochastic continuous-time algebraic Riccati equations (SCARE)\u0000typically arising from the differential statedependent Riccati equation\u0000technique from the 3D missile/target engagement, the F16 aircraft flight\u0000control and the quadrotor optimal control etc. To this end, we develop a fixed\u0000point (FP)-type iteration with solving a CARE by the structure-preserving\u0000doubling algorithm (SDA) at each iterative step, called FP-CARE SDA. We prove\u0000that either the FP-CARE SDA is monotonically nondecreasing or nonincreasing,\u0000and is R-linearly convergent, with the zero initial matrix or a special initial\u0000matrix satisfying some assumptions. The FP-CARE SDA (FPC) algorithm can be\u0000regarded as a robust initial step to produce a good initial matrix, and then\u0000the modified Newton (mNT) method can be used by solving the corresponding\u0000Lyapunov equation with SDA (FPC-mNT-Lyap SDA). Numerical experiments show that\u0000the FPC-mNT-Lyap SDA algorithm outperforms the other existing algorithms.","PeriodicalId":501061,"journal":{"name":"arXiv - CS - Numerical Analysis","volume":"231 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138517389","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"WENO based adaptive image zooming algorithm","authors":"Bojan Crnković, Jerko Škifić, Tina Bosner","doi":"arxiv-2312.00229","DOIUrl":"https://doi.org/arxiv-2312.00229","url":null,"abstract":"Image zooming or upsampling is a widely used tool in image processing and an\u0000essential step in many algorithms. Upsampling increases the number of pixels\u0000and introduces new information into the image, which can lead to numerical\u0000effects such as ringing artifacts, aliasing effects, and blurring of the image.\u0000In this paper, we propose an efficient polynomial interpolation algorithm based\u0000on the WENO algorithm for image upsampling that provides high accuracy in\u0000smooth regions, preserves edges and reduces aliasing effects. Although this is\u0000not the first application of WENO interpolation for image resampling, it is\u0000designed to have comparable complexity and memory load with better image\u0000quality than the separable WENO algorithm. We show that the algorithm performs equally well on smooth 2D functions,\u0000artificial pixel art, and real digital images. Comparison with similar methods\u0000on test images shows good results on standard metrics and also provides\u0000visually satisfactory results. Moreover, the low complexity of the algorithm is\u0000ensured by a small local approximation stencil and the appropriate choice of\u0000smoothness indicators.","PeriodicalId":501061,"journal":{"name":"arXiv - CS - Numerical Analysis","volume":"40 7","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-11-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138503950","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
L. Bialas-Ciez, D. J. Kenne, A. Sommariva, M. Vianello
{"title":"Evaluating Lebesgue constants by Chebyshev polynomial meshes on cube, simplex and ball","authors":"L. Bialas-Ciez, D. J. Kenne, A. Sommariva, M. Vianello","doi":"arxiv-2311.18656","DOIUrl":"https://doi.org/arxiv-2311.18656","url":null,"abstract":"We show that product Chebyshev polynomial meshes can be used, in a fully\u0000discrete way, to evaluate with rigorous error bounds the Lebesgue constant,\u0000i.e. the maximum of the Lebesgue function, for a class of polynomial projectors\u0000on cube, simplex and ball, including interpolation, hyperinterpolation and\u0000weighted least-squares. Several examples are presented and possible\u0000generalizations outlined. A numerical software package implementing the method\u0000is freely available online.","PeriodicalId":501061,"journal":{"name":"arXiv - CS - Numerical Analysis","volume":"41 3","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-11-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138503987","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Seung Won Suh, Seung Whan Chung, Peer-Timo Bremer, Youngsoo Choi
{"title":"Accelerating Flow Simulations using Online Dynamic Mode Decomposition","authors":"Seung Won Suh, Seung Whan Chung, Peer-Timo Bremer, Youngsoo Choi","doi":"arxiv-2311.18715","DOIUrl":"https://doi.org/arxiv-2311.18715","url":null,"abstract":"We develop an on-the-fly reduced-order model (ROM) integrated with a flow\u0000simulation, gradually replacing a corresponding full-order model (FOM) of a\u0000physics solver. Unlike offline methods requiring a separate FOM-only simulation\u0000prior to model reduction, our approach constructs a ROM dynamically during the\u0000simulation, replacing the FOM when deemed credible. Dynamic mode decomposition\u0000(DMD) is employed for online ROM construction, with a single snapshot vector\u0000used for rank-1 updates in each iteration. Demonstrated on a flow over a\u0000cylinder with Re = 100, our hybrid FOM/ROM simulation is verified in terms of\u0000the Strouhal number, resulting in a 4.4 times speedup compared to the FOM\u0000solver.","PeriodicalId":501061,"journal":{"name":"arXiv - CS - Numerical Analysis","volume":"41 11","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-11-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138503979","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Generalized Gearhart-Koshy acceleration is a Krylov space method of a new type","authors":"Markus Hegland, Janosch Rieger","doi":"arxiv-2311.18305","DOIUrl":"https://doi.org/arxiv-2311.18305","url":null,"abstract":"The Gearhart-Koshy acceleration for the Kaczmarz method for linear systems is\u0000a line-search with the unusual property that it does not minimize the residual,\u0000but the error. Recently one of the authors generalized the this acceleration\u0000from a line-search to a search in affine subspaces. In this paper, we demonstrate that the affine search is a Krylov space method\u0000that is neither a CG-type nor a MINRES-type method, and we prove that it is\u0000mathematically equivalent with a more canonical Gram-Schmidt-based method. We\u0000also investigate what abstract property of the Kaczmarz method enables this\u0000type of algorithm, and we conclude with a simple numerical example.","PeriodicalId":501061,"journal":{"name":"arXiv - CS - Numerical Analysis","volume":"354 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-11-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138517324","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}