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Time-fractional semilinear and quasilinear parabolic equations with a Caputo time derivative of order $\alpha\in(0,1)$ are considered, solutions of which exhibit a singular behaviour at an initial time of type $t^\sigma$ for any fixed…

Numerical Analysis · Mathematics 2026-01-26 Natalia Kopteva , Sean Kelly

In this paper, we study a $\tau$-matrix approximation based preconditioner for the linear systems arising from discretization of unsteady state Riesz space fractional diffusion equation with non-separable variable coefficients. The…

Numerical Analysis · Mathematics 2024-04-18 Xue-Lei Lin , Michael K. Ng

Our goal is to extend the denoising diffusion implicit model (DDIM) to general diffusion models~(DMs) besides isotropic diffusions. Instead of constructing a non-Markov noising process as in the original DDIM, we examine the mechanism of…

Machine Learning · Computer Science 2023-03-24 Qinsheng Zhang , Molei Tao , Yongxin Chen

Of primary interest in this paper is the numerical approximation of a time dependent fractional, in space, diffusion equation where the domain is assumed to be nonhomogeneous, having different axial diffusion coefficients. This work is…

Numerical Analysis · Mathematics 2026-05-12 T. Catoe , V. J. Ervin

In this work, we provide the first strong convergence result of numerical approximation of a general second order semilinear stochastic fractional order evolution equation involving a Caputo derivative in time of order $\alpha\in(\frac 34,…

Numerical Analysis · Mathematics 2021-09-08 Aurelien Junior Noupelah , Antoine Tambue

The coupled nonlinear space fractional Ginzburg-Landau (CNLSFGL) equations with the fractional Laplacian have been widely used to model the dynamical processes in a fractal media with fractional dispersion. Due to the existence of…

Numerical Analysis · Mathematics 2025-02-05 Hengfei Ding , Yuxin Zhang , Qian Yi

In this paper, we propose a new second-order fast finite difference scheme in time for solving the Tempered Time Fractional Advection-Dispersion Equation. Under the assumption that the solution is nonsmooth at the initial time, we…

Numerical Analysis · Mathematics 2025-12-22 Liangcai Huang , Shujuan Lü

This paper studies the spectral properties of large matrices and the preconditioning of linear systems, arising from the finite difference discretization of a time-dependent space-fractional diffusion equation with a variable coefficient…

Numerical Analysis · Mathematics 2026-03-17 Muhammad Faisal Khan , Asim Ilyas , Rolf Krause , Stefano Serra-Capizzano , Cristina Tablino-Possio

The aim of this paper is to numerically solve a diffusion differential problem having time derivative of fractional order. To this end we propose a collocation-Galerkin method that uses the fractional splines as approximating functions. The…

Numerical Analysis · Mathematics 2022-04-27 Laura Pezza , Francesca Pitolli

Computing numerical solutions to fractional differential equations can be computationally intensive due to the effect of non-local derivatives in which all previous time points contribute to the current iteration. In general, numerical…

Numerical Analysis · Mathematics 2016-05-04 Christopher L. MacDonald , Nirupama Bhattacharya , Brian P. Sprouse , Gabriel A. Silva

Fundamental solution of a space fractional convection equation of order $\alpha$ is the probability density function of L\'{e}vy flights with long-tailed $\alpha$-stable jump length distribution. By studying an upwind second-order implicit…

Numerical Analysis · Mathematics 2025-02-25 Lot-Kei Chou , Wan-Na Deng , Yuan-Yuan Huang , Siu-Long Lei

In this paper strong dissipativity of generalized time-fractional derivatives on Gelfand triples of properly in time weighted $L^p$-path spaces is proved. In particular, the classical Caputo derivative is included as a special case. As a…

Analysis of PDEs · Mathematics 2021-02-23 Wei Liu , Michael Röckner , José Luís da Silva

Two fast L1 time-stepping methods, including the backward Euler and stabilized semi-implicit schemes, are suggested for the time-fractional Allen-Cahn equation with Caputo's derivative. The time mesh is refined near the initial time to…

Numerical Analysis · Mathematics 2020-12-23 Bingquan Ji , Hong-lin Liao , Luming Zhang

An essential feature of the subdiffusion equations with the $\alpha$-order time fractional derivative is the weak singularity at the initial time. The weak regularity of the solution is usually characterized by a regularity parameter…

Numerical Analysis · Mathematics 2021-01-13 Dongfang Li , Hongyu Qin , Jiwei Zhang

This paper investigates quenching solutions of an one-dimensional, two-sided Riemann-Liouville fractional order convection-diffusion problem. Fractional order spatial derivatives are discretized using weighted averaging approximations in…

Analysis of PDEs · Mathematics 2025-03-06 Rumin Dong , Lin Zhu , Qin Sheng , Bingxin Zhao

The goal of the present work is to solve a linear dispersive equation with variable coefficient advection on an unbounded domain. In this setting, transparent boundary conditions are vital to allow waves to leave (or even re-enter) the,…

Numerical Analysis · Mathematics 2021-06-09 Lukas Einkemmer , Alexander Ostermann , Mirko Residori

We study solution techniques for an evolution equation involving second order derivative in time and the spectral fractional powers, of order $s \in (0,1)$, of symmetric, coercive, linear, elliptic, second-order operators in bounded domains…

Numerical Analysis · Mathematics 2018-06-18 Lehel Banjai , Enrique Otarola

This paper proposes and analyzes an implicit-explicit BDF-Galerkin scheme of second order for the time-dependent nonlinear thermistor problem. For this, we combine the second-order backward differentiation formula with special extrapolation…

Numerical Analysis · Mathematics 2026-05-29 R. Altmann , A. Moradi

In this paper, a new type of the discrete fractional Gr{\"o}nwall inequality is developed, which is applied to analyze the stability and convergence of a Galerkin spectral method for a linear time-fractional subdiffusion equation. Based on…

Numerical Analysis · Mathematics 2024-12-20 Yubo Yang , Fanhai Zeng

In this paper, we are interested in the study of a problem with fractional derivatives having boundary conditions of integral types. The problem represents a Caputo type advection-diffusion equation where the fractional order derivative…

Numerical Analysis · Mathematics 2021-02-23 Saadoune Brahimi , Ahcene Merad , Adem Kilicman