Series Solution of Differential Equations - Real or Fake?

Click For Summary

Discussion Overview

The discussion revolves around the validity and applicability of series solutions for nonlinear differential equations, particularly in relation to a Facebook group that claims to solve such equations. Participants explore the feasibility of these methods, their potential complications, and numerical approaches to related problems.

Discussion Character

  • Exploratory
  • Debate/contested
  • Technical explanation
  • Mathematical reasoning

Main Points Raised

  • One participant questions the legitimacy of a Facebook group's claims to solve any differential equation using series methods, expressing uncertainty about the feasibility and potential pitfalls of such approaches.
  • Another participant references a paper that may align with the Facebook group's claims, expressing skepticism about the complexity of analytic solutions compared to numerical solutions for the full problem.
  • A different participant notes that the series solutions from the Facebook group do not always manifest as power series of x, sometimes resulting in closed-form solutions or series involving functions like tanh().
  • There is a discussion about the numerical solution of a heat PDE in the (x,y) plane, with one participant inquiring about methods suitable for solving boundary value problems, specifically mentioning the shooting method.
  • Another participant confirms that the heat equation Dirichlet boundary value problem can be solved numerically and suggests using the finite analytic method, while also mentioning a notable error in a referenced textbook regarding the interpretation of solutions to the Schrödinger equation.

Areas of Agreement / Disagreement

Participants express varying levels of skepticism and curiosity regarding the claims made by the Facebook group, with no consensus on the validity of their methods or the best approaches to solving related differential equations.

Contextual Notes

Participants highlight the complexity of analytic solutions and the potential for errors in referenced materials, indicating that assumptions about the methods and their applicability may not be universally accepted.

Pejman
Messages
2
Reaction score
0
Hi guys,

I was browsing in regards to differential equations, the non-linear de and came up with this site in facebook:

https://www.facebook.com/nonlinearDE

Are these people for real? Can just solve any DE like that, come up with a series? Not an expert in this area, so I do not know what if this is actually possible? If it is possible, what are the downfalls?
Thanks.
 
Physics news on Phys.org
This paper may be relevant: http://arxiv.org/pdf/1206.2346.pdf. I'm not sure if it's the same people, but the authors seem to be claiming the same thing. I'm not sure I want analytic solutions if they have to be that complicated and ugly. Why not just have a numerical solution for the "full" problem and then compare that with simple analytic solutions that describe "parts" of whatever's going on?
 
Last edited:
Thanks a lot for the reply and paper, I looked through it and it seems similar, however, these fb guys series does not come as power series of x, some times it eventually become a closed form solution which I found very interesting, some times as power series of tanh() for example . They also have a heat PDE in (x,y) plane; I know that I had a similar problem but I had difficulties finding a numerical solution. Is it possible to find a numerical solution to this one? What method do you use? It's a BV problem, shooting method in 2-d?
 
If you mean the heat equation Dirichlet BV problem on the Facebook page then, yes, that can be solved numerically. I would probably use the finite analytic method on it. A good book to look at is the one by Richard Bernatz, Fourier Series and Numerical Methods for Partial Differential Equations. There is a rather egregious error in the front of the book (to a physicist, anyway!) where he says that the solution to the Schrödinger equation represents a velocity, but otherwise it's very good.
 

Similar threads

  • · Replies 3 ·
Replies
3
Views
2K
  • · Replies 3 ·
Replies
3
Views
2K
  • · Replies 4 ·
Replies
4
Views
3K
  • · Replies 9 ·
Replies
9
Views
3K
  • · Replies 3 ·
Replies
3
Views
3K
  • · Replies 5 ·
Replies
5
Views
6K
  • · Replies 0 ·
Replies
0
Views
4K
  • · Replies 2 ·
Replies
2
Views
2K
  • · Replies 2 ·
Replies
2
Views
6K
  • · Replies 3 ·
Replies
3
Views
2K