Understanding the Blow-Up Phenomenon in BVPs: y'' + ay' + e^{ax}y = 1

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Discussion Overview

The discussion revolves around the boundary value problem (BVP) defined by the equation y'' + ay' + e^{ax}y = 1, with boundary conditions y(0) = 0 and y(10) = 0. Participants explore the phenomenon of numerical blow-up at specific values of the parameter 'a' and seek to understand the underlying reasons and predictions for this behavior.

Discussion Character

  • Exploratory, Technical explanation, Debate/contested

Main Points Raised

  • One participant notes that the numerical solution to the BVP blows up at certain values of 'a', specifically around 0.089 and 0.2302, and questions the reasons behind this behavior.
  • Another participant suggests that the blow-up is related to the existence of a zero eigenvalue of the linear operator associated with the homogeneous equation, indicating that this could lead to an eigenfunction that diverges.
  • A participant seeks clarification on the variable 'x' in the context of the BVP.
  • Another participant confirms that 'y' is a function of 'x', addressing the previous query about the variable.

Areas of Agreement / Disagreement

Participants express differing levels of understanding regarding the blow-up phenomenon, with some proposing explanations while others seek clarification. The discussion remains unresolved regarding the exact nature of the blow-up and its prediction.

Contextual Notes

There are unresolved assumptions regarding the mathematical properties of the linear operator and the implications of the zero eigenvalue on the solutions of the BVP.

rsq_a
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I'm looking at the BVP:

[tex]y'' + ay' + e^{ax}y = 1[/tex],

with y(0) = 0 and y(10) = 0.

The numerical solution blows up at certain values of [tex]a[/tex]. For example, a near 0.089 and a near 0.2302. Why does this happen and how do I predict it?
 
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rsq_a said:
I'm looking at the BVP:

[tex]y'' + ay' + e^{ax}y = 1[/tex],

with y(0) = 0 and y(10) = 0.

The numerical solution blows up at certain values of [tex]a[/tex]. For example, a near 0.089 and a near 0.2302. Why does this happen and how do I predict it?

Erm. I found the problem. Near those values of 'a', there exists a zero eigenvalue of the linear operator. I guess that means that,

[tex]y'' + ay' + e^{ax}y = 0\cdot u^* = 1[/tex],

is a possible solution, and thus the eigenfunction [tex]u^* \to \infty[/tex] will cause the blowup.

Is this correct? It's been a while since I've done Sturm-Liouville stuff.
 
What is x?
 
jacophile said:
What is x?

[tex]y=y(x)[/tex]
 

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