{"title":"A Crank-Nicolson finite difference scheme for coupled nonlinear Schrödinger equations with saturable nonlinearity and nonlinear damping","authors":"Anh Ha Le , Quan M. Nguyen","doi":"10.1016/j.apnum.2025.09.007","DOIUrl":"10.1016/j.apnum.2025.09.007","url":null,"abstract":"<div><div>We propose a Crank-Nicolson finite difference scheme to simulate a 2D perturbed soliton interaction under the framework of coupled (2+1)D nonlinear Schrödinger equations with saturable nonlinearity and nonlinear damping. We rigorously demonstrate that the proposed numerical scheme achieves a second-order convergence rate in both the discrete <span><math><msubsup><mi>H</mi><mn>0</mn><mn>1</mn></msubsup></math></span> and <span><math><msup><mi>L</mi><mn>2</mn></msup></math></span> norms, relative to the time step and spatial mesh size. We establish the boundedness of discrete energies to prove the existence and uniqueness of the solutions derived from the Crank-Nicolson scheme. The validity of the analysis is confirmed through numerical simulations that apply to the corresponding coupled (2+1)D saturable nonlinear Schrödinger equations with damping terms.</div></div>","PeriodicalId":8199,"journal":{"name":"Applied Numerical Mathematics","volume":"219 ","pages":"Pages 219-238"},"PeriodicalIF":2.4,"publicationDate":"2025-09-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145118204","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}
Jialing Wang , Anxin Kong , Tingchun Wang , Wenjun Cai
{"title":"Point-wise error estimates of two mass- and energy-preserving schemes for two-dimensional Schrödinger–Poisson equations","authors":"Jialing Wang , Anxin Kong , Tingchun Wang , Wenjun Cai","doi":"10.1016/j.apnum.2025.09.006","DOIUrl":"10.1016/j.apnum.2025.09.006","url":null,"abstract":"<div><div>This work presents two implicit and linear finite difference schemes that simultaneously preserve both mass and energy conservation properties for the two-dimensional Schrödinger–Poisson equations. The conservation, existence, uniqueness, as well as the convergence to the exact solution with the order <span><math><mrow><mi>O</mi><mo>(</mo><msup><mi>τ</mi><mn>2</mn></msup><mo>+</mo><msubsup><mi>h</mi><mi>x</mi><mn>2</mn></msubsup><mo>+</mo><msubsup><mi>h</mi><mi>y</mi><mn>2</mn></msubsup><mo>)</mo></mrow></math></span> in discrete <span><math><msup><mi>L</mi><mn>2</mn></msup></math></span> and <span><math><msup><mi>L</mi><mi>∞</mi></msup></math></span> norms are established for these two schemes, where <span><math><mi>τ</mi></math></span> and <span><math><mrow><msub><mi>h</mi><mi>x</mi></msub><mo>,</mo><msub><mi>h</mi><mi>y</mi></msub></mrow></math></span> represent temporal and spatial step sizes. In contrast to the existing analysis techniques that rely on an <em>a priori</em> <span><math><msup><mi>L</mi><mi>∞</mi></msup></math></span> estimate of numerical solutions or impose restrictions on initial data, our approaches guarantee the unconditional convergence for SP equations with both attractive and repulsive forces. Besides the standard energy method, our analytical framework employs the cut-off method for the implicit scheme and the mathematical induction argument for the linear scheme, where the “lifting” technique is utilized in the two schemes to eliminate the constraints on grid ratios. Numerical experiments are provided to illustrate discrete conservation properties and validate the achieved convergence results.</div></div>","PeriodicalId":8199,"journal":{"name":"Applied Numerical Mathematics","volume":"219 ","pages":"Pages 202-218"},"PeriodicalIF":2.4,"publicationDate":"2025-09-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145106358","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 numerical method on a posteriori mesh for a singularly perturbed Riccati equation","authors":"Zhongdi Cen, Jian Huang, Aimin Xu","doi":"10.1016/j.apnum.2025.09.003","DOIUrl":"10.1016/j.apnum.2025.09.003","url":null,"abstract":"<div><div>In this paper a singularly perturbed Riccati equation is considered. A hybrid difference method is used to approximate the singularly perturbed Riccati equation. A posteriori error analysis for the discretization method on an arbitrary mesh is given. The stability result of the differential operator used in a posteriori error analysis is obtained based on the properties of the exact solution and the numerical solution. A solution-adaptive algorithm based on a posteriori error estimation is designed to generate a posteriori mesh and the approximation solution. Numerical experiments verify that the method is second-order uniformly convergent with respect to small parameter and improves previous results.</div></div>","PeriodicalId":8199,"journal":{"name":"Applied Numerical Mathematics","volume":"219 ","pages":"Pages 86-95"},"PeriodicalIF":2.4,"publicationDate":"2025-09-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145046507","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}
Maher Alwuthaynani , Muhammad Ahsan , Weidong Lei , Muhammad Abuzar , Masood Ahmad , Aditya Sharma
{"title":"A high-order Haar wavelet approach to solve differential equations of fifth-order with simple, two-point and two-point integral conditions","authors":"Maher Alwuthaynani , Muhammad Ahsan , Weidong Lei , Muhammad Abuzar , Masood Ahmad , Aditya Sharma","doi":"10.1016/j.apnum.2025.09.004","DOIUrl":"10.1016/j.apnum.2025.09.004","url":null,"abstract":"<div><div>This study introduces a high-order Haar wavelet collocation method (HHWCM) as an enhanced version of the classical Haar wavelet collocation method (HWCM) for solving fifth-order ordinary differential equations (FoDEs) subject to simple, two-point, and integral boundary conditions. By incorporating a quasi-linearization strategy, the proposed method avoids Jacobian computations and achieves higher accuracy with faster convergence. The stability and convergence of the approach are rigorously analyzed. Numerical experiments on both linear and nonlinear FoDEs demonstrate that HHWCM significantly outperforms HWCM and other existing numerical methods in terms of precision, computational efficiency, and robustness across diverse problem settings.</div></div>","PeriodicalId":8199,"journal":{"name":"Applied Numerical Mathematics","volume":"219 ","pages":"Pages 122-144"},"PeriodicalIF":2.4,"publicationDate":"2025-09-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145059915","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":"Comments on: “Two efficient iteration methods for solving the absolute value equations”","authors":"Chun-Hua Guo","doi":"10.1016/j.apnum.2025.09.005","DOIUrl":"10.1016/j.apnum.2025.09.005","url":null,"abstract":"<div><div>Two iterative methods for solving the absolute value equations are recently proposed and analyzed in the paper by Yu and Wu (Appl. Numer. Math. 208 (2025) 148–159). We point out that the convergence analysis for both methods is incorrect and that the second method with “optimal” parameters is always slightly <em>less</em> efficient than the well-known generalized Newton method.</div></div>","PeriodicalId":8199,"journal":{"name":"Applied Numerical Mathematics","volume":"219 ","pages":"Pages 96-98"},"PeriodicalIF":2.4,"publicationDate":"2025-09-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145046590","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 adaptive HDG method for the pointwise tracking optimal control problem of elliptic equations","authors":"Yanping Chen , Haitao Leng","doi":"10.1016/j.apnum.2025.09.001","DOIUrl":"10.1016/j.apnum.2025.09.001","url":null,"abstract":"<div><div>In this paper, we study an optimal control problem with point values of the state in the objective functional. The state and adjoint state are approximated by a hybridized discontinuous Galerkin (HDG) method, and the control is discretized by the variational discretization concept. With the help of the error estimates of Green’s function and Oswald interpolation, reliable and efficient a posteriori error estimates for the errors in the control, state and adjoint state variables are obtained. Several numerical examples are provided to show the performance of the obtained a posteriori error estimators.</div></div>","PeriodicalId":8199,"journal":{"name":"Applied Numerical Mathematics","volume":"219 ","pages":"Pages 73-85"},"PeriodicalIF":2.4,"publicationDate":"2025-09-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145046509","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":"Superconvergence of the local discontinuous Galerkin method with generalized numerical fluxes for one-dimensional linearized KdV equations","authors":"Yan Xu, Boying Wu, Xiong Meng","doi":"10.1016/j.apnum.2025.08.011","DOIUrl":"10.1016/j.apnum.2025.08.011","url":null,"abstract":"<div><div>In this paper, we analyze the local discontinuous Galerkin (LDG) method with generalized numerical fluxes to study the superconvergent properties of one-dimensional linearized KdV equations. Compared with traditional upwind and alternating fluxes, a slower error growth of the LDG solution using generalized numerical fluxes can be obtained for long time simulations. By establishing five energy identities and properties of correction functions with the appropriate numerical initial condition, we derive the supercloseness between the LDG solution and the interpolation function. The errors of the numerical fluxes as well as the cell averages achieve the <span><math><mrow><mo>(</mo><mn>2</mn><mi>k</mi><mo>+</mo><mn>1</mn><mo>)</mo></mrow></math></span>th-order superconvergence. In addition, we prove that the superconvergent rates of the function and derivative values at the interior generalized Radau points are <span><math><mrow><mi>k</mi><mo>+</mo><mn>2</mn></mrow></math></span> and <span><math><mrow><mi>k</mi><mo>+</mo><mn>1</mn></mrow></math></span>, respectively. An extension to mixed boundary conditions is given, for which we present the generalized skew-symmetry property and propose an appropriate conservation property for the numerical initial condition. Numerical experiments are shown to demonstrate the theoretical results, including cases with other boundary conditions and nonlinear KdV equations.</div></div>","PeriodicalId":8199,"journal":{"name":"Applied Numerical Mathematics","volume":"219 ","pages":"Pages 99-121"},"PeriodicalIF":2.4,"publicationDate":"2025-09-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145057114","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 recovery of boundary impedance for 3-dimensional obstacle by acoustic wave scattering using modified Kaczmarz iteration algorithm","authors":"Yingdi Yi, Jijun Liu","doi":"10.1016/j.apnum.2025.08.010","DOIUrl":"10.1016/j.apnum.2025.08.010","url":null,"abstract":"<div><div>The boundary impedance coefficient for an impenetrable obstacle represents its absorption ability for the incident waves, and consequently its indirect detection is of great importance in remote sensing, with the aim of detecting the property of obstacle boundary. We address an inverse acoustic scattering problem for a three-dimensional obstacle, focusing on the reconstruction of boundary impedance using the far-field pattern of the scattered wave corresponding to given incident plane waves. A two-point gradient method combined with the Kaczmarz type scheme is proposed to obtain satisfactory reconstruction. The iteration scheme is formulated by applying the adjoint operator for the forward scattering, based on the potential representation of the scattered wave. The convergence property of the iteration process is rigorously proved. To address the computational scheme for the surface potentials, we use an efficient numerical scheme tailored for three-dimensional geometries. Numerical experiments are presented to demonstrate the validity and robustness of our proposed approach.</div></div>","PeriodicalId":8199,"journal":{"name":"Applied Numerical Mathematics","volume":"219 ","pages":"Pages 53-72"},"PeriodicalIF":2.4,"publicationDate":"2025-09-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145046508","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 highly accurate symplectic-preserving scheme for Gross-Pitaevskii equation","authors":"Lan Wang , Yiyang Luo , Meng Chen , Pengfei Zhu","doi":"10.1016/j.apnum.2025.08.006","DOIUrl":"10.1016/j.apnum.2025.08.006","url":null,"abstract":"<div><div>An efficient fourth-order numerical scheme is developed for the Gross-Pitaevskii equation. The spatial direction is approximated by a fourth-order compact scheme and the temporal direction is discretized by a fourth-order splitting & composition method. This scheme not only preserves the symplectic structure and the discrete mass conservation law exactly but also maintains the discrete energy conservation law in some special case. Some numerical experiments confirm our theoretical expectation.</div></div>","PeriodicalId":8199,"journal":{"name":"Applied Numerical Mathematics","volume":"219 ","pages":"Pages 41-52"},"PeriodicalIF":2.4,"publicationDate":"2025-09-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145044374","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}
Zikang Qin , Xiaoyu Duan , Hengbin An , Haoxuan Zhang , Shaoliang Hu
{"title":"CSCMO: Relative permittivity-based complex shifted operator preconditioning method for solving time-harmonic Maxwell equations","authors":"Zikang Qin , Xiaoyu Duan , Hengbin An , Haoxuan Zhang , Shaoliang Hu","doi":"10.1016/j.apnum.2025.08.009","DOIUrl":"10.1016/j.apnum.2025.08.009","url":null,"abstract":"<div><div>In electromagnetic field modeling and simulation, a critical challenge lies in solving discretized time-harmonic Maxwell equations. The inherent complexity of these systems – including matrix indefiniteness and solution oscillations – poses significant difficulties for efficient numerical solutions. Preconditioned Krylov subspace methods have emerged as a standard approach for solving the large scale discretized time-harmonic Maxwell equations, where the construction of effective preconditioners remains pivotal. The shifted operator method represents a prominent preconditioning technique for Maxwell equations. Typically, a purely imaginary shift to the original differential operator is used, since this capitalizes on the observed phenomenon where solution oscillatory behavior diminishes with increasing modulus of the imaginary component of relative permittivity. In this paper, we propose a novel preconditioning technique by shifting both the real and imaginary parts of the relative permittivity. The motivation for proposing this kind of shifted operator preconditioning is based on theoretical analysis, which shows that decreasing the real part of the relative permittivity will improve the positive definiteness of the discretized matrix. The resulting preconditioned system admits efficient solution via multigrid methods. Some analysis shows that the spectral distribution of the preconditioned matrix is more clustered than the purely imaginary shift preconditioned matrix. Also, theoretical analysis for a special model shows that the condition number of the preconditioned system is less than its purely imaginary-shifted counterpart. Numerical results demonstrate that the proposed preconditioning is more effective than the other two state-of-the-art shift operator preconditioning methods.</div></div>","PeriodicalId":8199,"journal":{"name":"Applied Numerical Mathematics","volume":"219 ","pages":"Pages 145-169"},"PeriodicalIF":2.4,"publicationDate":"2025-09-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145106356","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}