Journal of Computational and Applied Mathematics最新文献_第8页

Fast numerical derivatives of univariate functions on non-uniform grids 非均匀网格上单变量函数的快速数值导数

IF 2.1 2区数学

Journal of Computational and Applied Mathematics Pub Date : 2025-03-08 DOI: 10.1016/j.cam.2025.116619

Nadaniela Egidi, Josephin Giacomini, Pierluigi Maponi

引用次数: 0

A sharpening median filter for Cauchy noise with wavelet based regularization 基于小波正则化的柯西噪声锐化中值滤波器

IF 2.1 2区数学

Journal of Computational and Applied Mathematics Pub Date : 2025-03-07 DOI: 10.1016/j.cam.2025.116625

Xiao Ai , Guoxi Ni , Tieyong Zeng

引用次数: 0

Solution of linear ill-posed operator equations by modified truncated singular value expansion 线性病态算子方程的修正截断奇异值展开解

IF 2.1 2区数学

Journal of Computational and Applied Mathematics Pub Date : 2025-03-07 DOI: 10.1016/j.cam.2025.116621

Laura Dykes , Mykhailo Kuian , Thomas Mach , Silvia Noschese , Lothar Reichel

{"title":"Solution of linear ill-posed operator equations by modified truncated singular value expansion","authors":"Laura Dykes , Mykhailo Kuian , Thomas Mach , Silvia Noschese , Lothar Reichel","doi":"10.1016/j.cam.2025.116621","DOIUrl":"10.1016/j.cam.2025.116621","url":null,"abstract":"<div><div>In much of the literature on the solution of linear ill-posed operator equations in a Hilbert space, the operator equation first is discretized, then the discretized operator is regularized, and finally, the computed solution of the regularized discrete problem is projected into a Hilbert space. In order for this solution approach to give an accurate approximate solution, the regularization method has to correspond to a meaningful analogue in Hilbert space. Moreover, the regularization method chosen may only be applicable to certain linear ill-posed operator equations. However, these issues typically are not discussed in the literature on solution methods based on discretization. One approach to circumvent this difficulty is to avoid discretization. This paper describes how regularization by a modified truncated singular value decomposition introduced in Noschese and Reichel (2014) for finite-dimensional problems can be extended to operator equations. In finite dimensions, this regularization method yields approximate solutions of higher quality than standard truncated singular value decomposition. Our analysis in a Hilbert space setting is of practical interest, because the solution method presented avoids the introduction of discretization errors during the solution process, since we compute regularized solutions without discretization by using the program package Chebfun. While this paper focuses on a particular regularization method, the analysis presented and Chebfun also can be applied to other regularization techniques.</div></div>","PeriodicalId":50226,"journal":{"name":"Journal of Computational and Applied Mathematics","volume":"467 ","pages":"Article 116621"},"PeriodicalIF":2.1,"publicationDate":"2025-03-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143611554","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}

引用次数: 0

New upper bounds for the q-numerical radii of 2×2 operator matrices 2×2算子矩阵的q数值半径的新上界

IF 2.1 2区数学

Journal of Computational and Applied Mathematics Pub Date : 2025-03-06 DOI: 10.1016/j.cam.2025.116618

Fuad Kittaneh , M.H.M. Rashid

引用次数: 0

Optimal error estimates of second-order weighted virtual element method for nonlinear coupled prey–predator equation 非线性耦合捕食-捕食方程二阶加权虚元法的最优误差估计

IF 2.1 2区数学

Journal of Computational and Applied Mathematics Pub Date : 2025-03-06 DOI: 10.1016/j.cam.2025.116617

Yanping Chen , Shanshan Peng

{"title":"Optimal error estimates of second-order weighted virtual element method for nonlinear coupled prey–predator equation","authors":"Yanping Chen , Shanshan Peng","doi":"10.1016/j.cam.2025.116617","DOIUrl":"10.1016/j.cam.2025.116617","url":null,"abstract":"<div><div>In this paper, we develop a numerical method for solving the nonlinear coupled prey–predator equation on arbitrary polygonal meshes, employing the virtual element method for spatial discretization and a second-order weighted method for temporal discretization. We rigorously establish the existence, uniqueness and convergence of solutions using Schaefer’s fixed point theorem. Moreover, we derive an optimal error estimate in the <span><math><msup><mrow><mi>H</mi></mrow><mrow><mn>1</mn></mrow></msup></math></span>-norm that is independent of any spatial–temporal grid ratio constraints. This approach eliminates the need for the time semi-discrete system that would otherwise be introduced by temporal–spatial error splitting techniques, thereby streamlining the computational process. By adjusting the weighted parameter <span><math><mi>θ</mi></math></span>, the second-order weighted scheme seamlessly transitions to classic methods such as Crank–Nicolson (<span><math><mrow><mi>θ</mi><mo>=</mo><mn>0</mn><mo>.</mo><mn>5</mn></mrow></math></span>) and two-step backward differentiation formula method (<span><math><mrow><mi>θ</mi><mo>=</mo><mn>1</mn></mrow></math></span>). Finally, numerical experiments confirm the validity of our theoretical results.</div></div>","PeriodicalId":50226,"journal":{"name":"Journal of Computational and Applied Mathematics","volume":"467 ","pages":"Article 116617"},"PeriodicalIF":2.1,"publicationDate":"2025-03-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143580627","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}

引用次数: 0

Analysis of a generalized MASSOR method for saddle point problems 鞍点问题的广义MASSOR方法分析

IF 2.1 2区数学

Journal of Computational and Applied Mathematics Pub Date : 2025-03-06 DOI: 10.1016/j.cam.2025.116626

Changfeng Ma , Xiaojuan Yu

引用次数: 0

Regularized Nesterov’s accelerated damped BFGS method for stochastic optimization 随机优化的正则Nesterov加速阻尼BFGS方法

IF 2.1 2区数学

Journal of Computational and Applied Mathematics Pub Date : 2025-03-05 DOI: 10.1016/j.cam.2025.116616

Siwakon Suppalap , Dawrawee Makmuang , Vipavee Damminsed , Rabian Wangkeeree

{"title":"Regularized Nesterov’s accelerated damped BFGS method for stochastic optimization","authors":"Siwakon Suppalap , Dawrawee Makmuang , Vipavee Damminsed , Rabian Wangkeeree","doi":"10.1016/j.cam.2025.116616","DOIUrl":"10.1016/j.cam.2025.116616","url":null,"abstract":"<div><div>A regularization term is introduced into the approximate Hessian update in the stochastic Broyden–Fletcher–Goldfarb–Shanno (BFGS) method for convex stochastic optimization problems to help avoid near-singularity issues. Additionally, Nesterov acceleration, with a momentum coefficient that dynamically adjusts between a constant value and zero based on the objective function, has been incorporated to enhance convergence speed. However, the inflexibility of the constant momentum coefficient still may lead to overshooting problems, and evaluating objective functions on large datasets is computationally costly. Moreover, this approach presents challenges in solving nonconvex optimization problems. To address these challenges, we propose a regularized stochastic BFGS method that integrates Nesterov acceleration with an adaptive momentum coefficient designed for solving nonconvex stochastic optimization problems. This coefficient adjusts flexibly between a decreasing value and zero based on selected dataset samples, helping to avoid overshooting problems and reduce computational costs. We demonstrated almost sure convergence to stationary points and analyze the complexity. Numerical results on convex and nonconvex classification problems using a support vector machine show that our method outperforms existing approaches.</div></div>","PeriodicalId":50226,"journal":{"name":"Journal of Computational and Applied Mathematics","volume":"467 ","pages":"Article 116616"},"PeriodicalIF":2.1,"publicationDate":"2025-03-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143580628","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}

引用次数: 0

A discrete-time queue with service time adjustments and general retrial times 具有服务时间调整和一般重审时间的离散时间队列

IF 2.1 2区数学

Journal of Computational and Applied Mathematics Pub Date : 2025-03-05 DOI: 10.1016/j.cam.2025.116605

Iván Atencia, José Luis Galán-García, Yolanda Padilla-Domínguez, Pedro Rodríguez-Cielos

{"title":"A discrete-time queue with service time adjustments and general retrial times","authors":"Iván Atencia, José Luis Galán-García, Yolanda Padilla-Domínguez, Pedro Rodríguez-Cielos","doi":"10.1016/j.cam.2025.116605","DOIUrl":"10.1016/j.cam.2025.116605","url":null,"abstract":"<div><div>This paper examines a discrete-time retrial queueing system where incoming customers can either choose a last-come, first-served (LCFS) discipline or enter an orbit. It accounts for the possibility of varying service times, which follow an arbitrary distribution, and the retrial times are also governed by an arbitrary distribution. The underlying Markov chain of the system has been analyzed, leading to the derivation of the generating function for the number of customers in both the orbit and the overall system, along with their expected values. The paper also establishes the stochastic decomposition law and, as an application, provides bounds for the difference between the steady-state distributions of the system in question and its standard equivalent. Recursive formulas for determining the steady-state distribution of customers in the orbit and the system are presented. The paper derives the distribution of the time a customer spends at the server and, consequently, the distribution of service times subject to possible variations. A detailed analysis of the time a customer spends in the orbit is also conducted. Finally, numerical examples are included to demonstrate how key parameters impact various system characteristics, with the main contributions of the research summarized in the conclusion.</div></div>","PeriodicalId":50226,"journal":{"name":"Journal of Computational and Applied Mathematics","volume":"467 ","pages":"Article 116605"},"PeriodicalIF":2.1,"publicationDate":"2025-03-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143571484","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}

引用次数: 0

Dual Neural Network (DuNN) method for elliptic partial differential equations and systems 椭圆型偏微分方程和系统的对偶神经网络（DuNN）方法

IF 2.1 2区数学

Journal of Computational and Applied Mathematics Pub Date : 2025-03-05 DOI: 10.1016/j.cam.2025.116596

Min Liu , Zhiqiang Cai , Karthik Ramani

引用次数: 0

Spectral approximated superconvergent method for nonlinear Volterra Hammerstein integral equations with weakly singular kernels 弱奇异核非线性Volterra Hammerstein积分方程的谱逼近超收敛方法

IF 2.1 2区数学

Journal of Computational and Applied Mathematics Pub Date : 2025-03-03 DOI: 10.1016/j.cam.2025.116601

Samiran Chakraborty , Shivam Kumar Agrawal , Gnaneshwar Nelakanti

引用次数: 0