Can Green Functions Help Solve Differential Equations?

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Discussion Overview

The discussion revolves around the use of Green functions in solving differential equations, specifically exploring how to construct a differential operator L given a Green function G(x,s). The conversation includes theoretical aspects and mathematical reasoning related to differential equations and transforms.

Discussion Character

  • Exploratory
  • Mathematical reasoning

Main Points Raised

  • One participant states that for a given differential equation of the form Ly=a0(x)y+a1(x)Dy+a2(x)D^2y=0, a Green function can be constructed such that LG(x,s)=d(x-s), where d is the delta function.
  • Another participant hints that the Fourier transform of the Green function is related to the inverse of the Fourier transform of the linear differential operator.
  • A subsequent reply suggests a relationship involving the Fourier transform, questioning if the same principle applies with the Laplace transform.
  • One participant expresses a lack of familiarity with the use of Green functions in conjunction with Laplace transforms, noting that Cauchy problems in linear ordinary differential equations are typically addressed using Laplace transforms.

Areas of Agreement / Disagreement

Participants do not appear to reach a consensus on the relationship between Green functions and differential operators, as well as the applicability of Laplace transforms in this context. Multiple viewpoints and uncertainties remain present in the discussion.

Contextual Notes

There are limitations regarding the assumptions made about the relationship between Green functions and differential operators, as well as the specific conditions under which these mathematical tools are applied. The discussion does not resolve these aspects.

eljose
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we all know that given a differential equation Ly=a0(x)y+a1(x)Dy+a2(x)D^2y=0 with Dy=dy/dx we can construct a Green function so LG(x,s)=d(x-s) being d the delta function.

My question is this given the G(x,s) could we construct the L so LG(x,s)=d(x-s) could someone provide an example of how to obtain?..thanks.
 
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HINT:Fourier transformed of the Green function coincides with the inverse of the Fourier transformed of the LINEAR differential operator...

Daniel.

P.S.Think aboout Poisson's equation for an infinite domain.
 
You mean F[G(x,s)]=1/F[L(y)] so then F^-1[1/G(x,s)]=L(y) does the same happen with the Laplace transform?...
 
I've never used Green functions and Laplace transforms...I told you what i knew...Maybe someone else could enlighten you more.

What i do know is that Cauchy problems in LINEAR ode's are dealt nicely by Laplace transform...But i don't recall some Green functions having been used...

Daniel.
 

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