Analytical Solutions of Systems of Linear Delay Differential Equations by the Laplace Transform: Featuring Limit Cycles

In this paper we develop an approach for obtaining the solutions to systems of linear retarded and neutral delay differential equations. Our analytical approach is based on the Laplace transform, inverse Laplace transform and the Cauchy residue theorem. The obtained solutions have the form of infini...

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Main Authors: Gilbert Kerr, Nehemiah Lopez, Gilberto González-Parra
Format: Article
Language:English
Published: MDPI AG 2024-02-01
Series:Mathematical and Computational Applications
Subjects:
Online Access:https://www.mdpi.com/2297-8747/29/1/11
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author Gilbert Kerr
Nehemiah Lopez
Gilberto González-Parra
author_facet Gilbert Kerr
Nehemiah Lopez
Gilberto González-Parra
author_sort Gilbert Kerr
collection DOAJ
description In this paper we develop an approach for obtaining the solutions to systems of linear retarded and neutral delay differential equations. Our analytical approach is based on the Laplace transform, inverse Laplace transform and the Cauchy residue theorem. The obtained solutions have the form of infinite non-harmonic Fourier series. The main advantage of the proposed approach is the closed-form of the solutions, which are capable of accurately evaluating the solution at any time. Moreover, it allows one to study the asymptotic behavior of the solutions. A remarkable discovery, which to the best of our knowledge has never been presented in the literature, is that there are some particular linear systems of both retarded and neutral delay differential equations for which the solution asymptotically approaches a limit cycle. The well-known method of steps in many cases is unable to obtain the asymptotic behavior of the solution and would most likely fail to detect such cycles. Examples illustrating the Laplace transform method for linear systems of DDEs are presented and discussed. These examples are designed to facilitate a discussion on how the spectral properties of the matrices determine the manner in which one proceeds and how they impact the behavior of the solution. Comparisons with the exact solution provided by the method of steps are presented. Finally, we should mention that the solutions generated by the Laplace transform are, in most instances, extremely accurate even when the truncated series is limited to only a handful of terms and in many cases become more accurate as the independent variable increases.
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spelling doaj.art-d6b0fe73c80a45d2902674ea009af8392024-02-23T15:26:21ZengMDPI AGMathematical and Computational Applications1300-686X2297-87472024-02-012911110.3390/mca29010011Analytical Solutions of Systems of Linear Delay Differential Equations by the Laplace Transform: Featuring Limit CyclesGilbert Kerr0Nehemiah Lopez1Gilberto González-Parra2Department of Mathematics, New Mexico Tech, Socorro, NM 87801, USADepartment of Mathematics, New Mexico Tech, Socorro, NM 87801, USADepartment of Mathematics, New Mexico Tech, Socorro, NM 87801, USAIn this paper we develop an approach for obtaining the solutions to systems of linear retarded and neutral delay differential equations. Our analytical approach is based on the Laplace transform, inverse Laplace transform and the Cauchy residue theorem. The obtained solutions have the form of infinite non-harmonic Fourier series. The main advantage of the proposed approach is the closed-form of the solutions, which are capable of accurately evaluating the solution at any time. Moreover, it allows one to study the asymptotic behavior of the solutions. A remarkable discovery, which to the best of our knowledge has never been presented in the literature, is that there are some particular linear systems of both retarded and neutral delay differential equations for which the solution asymptotically approaches a limit cycle. The well-known method of steps in many cases is unable to obtain the asymptotic behavior of the solution and would most likely fail to detect such cycles. Examples illustrating the Laplace transform method for linear systems of DDEs are presented and discussed. These examples are designed to facilitate a discussion on how the spectral properties of the matrices determine the manner in which one proceeds and how they impact the behavior of the solution. Comparisons with the exact solution provided by the method of steps are presented. Finally, we should mention that the solutions generated by the Laplace transform are, in most instances, extremely accurate even when the truncated series is limited to only a handful of terms and in many cases become more accurate as the independent variable increases.https://www.mdpi.com/2297-8747/29/1/11systems of linear delay differential equationsretardedneutralLaplace transformnon-harmonic Fourier serieslimit cycles
spellingShingle Gilbert Kerr
Nehemiah Lopez
Gilberto González-Parra
Analytical Solutions of Systems of Linear Delay Differential Equations by the Laplace Transform: Featuring Limit Cycles
Mathematical and Computational Applications
systems of linear delay differential equations
retarded
neutral
Laplace transform
non-harmonic Fourier series
limit cycles
title Analytical Solutions of Systems of Linear Delay Differential Equations by the Laplace Transform: Featuring Limit Cycles
title_full Analytical Solutions of Systems of Linear Delay Differential Equations by the Laplace Transform: Featuring Limit Cycles
title_fullStr Analytical Solutions of Systems of Linear Delay Differential Equations by the Laplace Transform: Featuring Limit Cycles
title_full_unstemmed Analytical Solutions of Systems of Linear Delay Differential Equations by the Laplace Transform: Featuring Limit Cycles
title_short Analytical Solutions of Systems of Linear Delay Differential Equations by the Laplace Transform: Featuring Limit Cycles
title_sort analytical solutions of systems of linear delay differential equations by the laplace transform featuring limit cycles
topic systems of linear delay differential equations
retarded
neutral
Laplace transform
non-harmonic Fourier series
limit cycles
url https://www.mdpi.com/2297-8747/29/1/11
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AT gilbertogonzalezparra analyticalsolutionsofsystemsoflineardelaydifferentialequationsbythelaplacetransformfeaturinglimitcycles