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Initial-boundary value problems for 1-dimensional `completely integrable' equations can be solved via an extension of the inverse scattering method, which is due to Fokas and his collaborators. A crucial feature of this method is that it…

Analysis of PDEs · Mathematics 2021-06-15 Dimitra C. Antonopoulou , Spyridon Kamvissis

A new method for the solution of initial-boundary value problems for evolution PDEs recently introduced by Fokas is generalised to multidimensions. Also the relation of this method with the method of images and with the classical integral…

Condensed Matter · Physics 2007-05-23 Athanassios S. Fokas , Daniel ben-Avraham

The Fast Fourier Transform is extended to functions on finite graphs whose edges are identified with intervals of finite length. Spectral and pseudospectral methods are developed to solve a wide variety of time dependent partial…

Numerical Analysis · Mathematics 2025-07-11 Robert Carlson

A large class of initial-boundary value problems of linear evolution partial differential equations formulated on the half-line is analyzed via the unified transform method. In particular, explicit formulae are presented for the generalized…

Analysis of PDEs · Mathematics 2016-04-21 Athanassios S. Fokas , Zipeng Wang

We study the diffusion (or heat) equation on a finite 1-dimensional spatial domain, but we replace one of the boundary conditions with a "nonlocal condition", through which we specify a weighted average of the solution over the spatial…

Analysis of PDEs · Mathematics 2017-08-04 Peter D. Miller , David A. Smith

In this study, we derive an analytical solution to address the problem of one-dimensional vertical infiltration within bounded profiles. We consider the Richards equation together with various boundary conditions, simulating different…

Analysis of PDEs · Mathematics 2025-03-25 Ioannis Argyrokastritis , Konstantinos Kalimeris , Leonidas Mindrinos

This paper presents a new numerical method which approximates Neumann type null controls for the heat equation and is based on the Fokas method. This is a direct method for solving problems originating from the control theory, which allows…

Numerical Analysis · Mathematics 2023-01-18 Konstantinos Kalimeris , Türker Özsarı , Nikolaos Dikaios

The initial-boundary value problem for the Kundu--Eckhaus equation on the half-line is considered in this paper by using the Fokas method. We will show that the solution $u(x,t)$ can be expressed in terms of the solution of a matrix…

Analysis of PDEs · Mathematics 2017-12-12 Boling Guo , Nan Liu

Originating from the mathematical modelling of rainfall infiltration, we derive the solution of an initial-boundary value problem of a linear evolution partial differential equation, by using the Fokas method. We present numerical examples…

Analysis of PDEs · Mathematics 2024-10-23 Konstantinos Kalimeris , Leonidas Mindrinos

The solution of an initial-boundary value problem for a linear evolution partial differential equation posed on the half-line can be represented in terms of an integral in the complex (spectral) plane. This representation is obtained by the…

Analysis of PDEs · Mathematics 2016-02-09 Beatrice Pelloni , David A. Smith

In [Proc. Roy. Soc. London Ser. A 453 (1997), no. 1962, 1411-1443] A.S. Fokas introduced a novel method for solving a large class of boundary value problems associated with evolution equations. This approach relies on the construction of a…

Analysis of PDEs · Mathematics 2008-04-25 Anthony C. L. Ashton

This paper deals with numerical solutions to a partial differential equation of fractional order. Generally this type of equation describes a transition from anomalous diffusion to transport processes. From a phenomenological point of view,…

Numerical Analysis · Mathematics 2007-05-23 Mariusz Ciesielski , Jacek Leszczynski

In this paper, we focus on one-dimensional vertical infiltration, assuming constant diffusivity and a quadratic relationship between hydraulic conductivity and water content. Under these assumptions, Richards' equation reduces to Burgers'…

Analysis of PDEs · Mathematics 2026-05-26 Konstantinos Kalimeris , Leonidas Mindrinos , Athanasios Paraskevopoulos

This work studies the initial-boundary value problem for both the linear Schr\"odinger equation and the cubic nonlinear Schr\"odinger equation on the half-space in higher dimensions ($n\ge 2$). First, the forced linear problem is solved on…

Analysis of PDEs · Mathematics 2024-11-26 A. Alexandrou Himonas , Fangchi Yan

The initial-boundary value problem (ibvp) for the $m$-th order dispersion Korteweg-de Vries (KdV) equation on the half-line with rough data and solution in restricted Bourgain spaces is studied using the Fokas Unified Transform Method…

Analysis of PDEs · Mathematics 2022-06-16 A. Alexanddrou Himonas , Fangchi Yan

We describe a new form of diagonalization for linear two point constant coefficient differential operators with arbitrary linear boundary conditions. Although the diagonalization is in a weaker sense than that usually employed to solve…

Spectral Theory · Mathematics 2021-10-22 Sultan Aitzhan , Sambhav Bhandari , David Andrew Smith

Boundary value problems for integrable nonlinear evolution PDEs formulated on the half-line can be analyzed by the unified method introduced by one of the authors and used extensively in the literature. The implementation of this general…

Analysis of PDEs · Mathematics 2015-05-30 A. S. Fokas , J. Lenells

A numerical method to solve the fractional diffusion equation, which could also be easily extended to many other fractional dynamics equations, is considered. These fractional equations have been proposed in order to describe anomalous…

Numerical Analysis · Mathematics 2025-10-20 S. B. Yuste , L. Acedo

In this paper we explain how to use the Fast Fourier Transform (FFT) to solve partial differential equations (PDEs). We start by defining appropriate discrete domains in coordinate and frequency domains. Then describe the main limitation of…

Numerical Analysis · Mathematics 2025-07-31 Daniela Rodriguez-Lara , Ivan Alvarez-Rios , Francisco S. Guzman

We study an initial value problem for the one-dimensional non-stationary linear Schr\"odinger equation with a point singular potential. In our approach, the problem is considered as a system of coupled initial-boundary value (IBV) problems…

Analysis of PDEs · Mathematics 2020-04-14 Yan Rybalko