Is there a function that equals its Laplace transform?

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Discussion Overview

The discussion revolves around the existence of functions that are equal to their Laplace transform, specifically inquiring about the eigenfunctions of the Laplace transform when λ=1. The scope includes theoretical exploration of mathematical properties related to the Laplace transform.

Discussion Character

  • Exploratory, Technical explanation, Debate/contested

Main Points Raised

  • One participant questions the availability of information on functions that equal their Laplace transform and seeks insights on this problem.
  • Another participant states that for a function to be its own Laplace transform, it must satisfy the equation $$F(s) = \int_0^\infty f(t)e^{-st}dt = f(s)$$ and expresses doubt about the existence of such functions, noting it has been discussed previously.
  • A third participant reiterates the equation for a function to be its own Laplace transform and agrees with the previous claim regarding real functions, while suggesting that complex functions may have multiple solutions, hinting at the existence of at least one example.
  • A later reply expresses a light-hearted acknowledgment of the complexity of the discussion.

Areas of Agreement / Disagreement

Participants do not reach a consensus on the existence of functions that are equal to their Laplace transform, with some suggesting that real functions do not satisfy this condition while others propose that complex functions may have solutions.

Contextual Notes

The discussion lacks definitive proofs or examples, and the nature of the functions being considered (real vs. complex) introduces additional complexity that remains unresolved.

Bipolarity
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Google seems to provide not much information on this. In essence, I am asking about the eigenfunctions of the Laplace transform when λ=1? Anyone have any insights on this rather unusual problem?

BiP
 
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Simon Bridge said:
You want: $$F(s) = \int_0^\infty f(t)e^{-st}dt = f(s)$$ ... for a function to be it's own Laplace transform.
Been discussed before:
https://www.physicsforums.com/archive/index.php/t-180250.html
I don't think there is any F(s)=f(s) ... but I'd be hard pressed to prove it.
I agree in case of real function.
In case of complex function, there are many solutions. For example, one of them :
 

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Yike - well there you have it :)
 

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