Infinite series solution for NON-linear ODEs?

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Discussion Overview

The discussion centers on the applicability of the infinite series method, specifically the Frobenius method, for obtaining general solutions of non-linear ordinary differential equations (ODEs). Participants explore the feasibility of using power series expansions for non-linear cases, particularly for second-order equations, and seek references for further study.

Discussion Character

  • Debate/contested

Main Points Raised

  • One participant questions whether the infinite series method can be applied to non-linear ODEs and expresses interest in second-order equations.
  • Another participant asserts that Frobenius' method and series methods generally assume the ability to "add" solutions, which they claim is only valid for linear differential equations.
  • A different participant argues that non-linear ODEs can indeed be solved using power series expansions and seeks specific references to avoid unnecessary effort in rediscovering existing methods.
  • One participant suggests that for first-order differential equations, the power series method may be applicable due to the existence and uniqueness theorem, while mentioning the Adomian method as a potentially useful iterative approach for higher-order equations.

Areas of Agreement / Disagreement

Participants express differing views on the applicability of series methods to non-linear ODEs, with some asserting it is not possible while others believe it can be done. The discussion remains unresolved regarding the effectiveness and validity of these methods for non-linear cases.

Contextual Notes

Participants reference the existence and uniqueness theorem and the Adomian method, indicating potential limitations in their understanding or application of these concepts. There is also a noted uncertainty about the convergence of series solutions for non-linear ODEs.

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infinite series solution for NON-linear ODEs?

Is it possible to use the infinite series method (Frobenius) to obtain general solutions of non-linear ODE's, I want to try a second order equation. Any good references where I can see how that goes exactly?
 
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No. Frobenius' method and series methods in general assume that you can "add" solutions. That is only true for linear differential equations.
 


The solution of a non-linear ODE is a function that can be expanded in power series and I've actually seen non-linear ODE's solved that way. The question is wether there is a book/article that focuses specifically on such type of solving cause I don't want to spend months reinventing the wheel and the hot water?
 


May be for first order DE it is possible to use power series method because of the existence and uniqueness theorem.

For higher order, if you are still interested in series solution, try the Adomian method. I understand that it is an iterative method but the series obtained converges quickly (please forgive me if I'm wrong. I only saw it in seminars. Hopefully I will be able to learn properly this method one day)
 

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