Is this Fourier transformation an eigenproblem?

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    Fourier Transformation
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Discussion Overview

The discussion revolves around the nature of the Fourier transformation as an operator, specifically whether it can be classified as an eigenproblem and the implications of its symmetry and unitary properties. Participants explore definitions and contexts related to these concepts.

Discussion Character

  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant questions whether it is appropriate to refer to the Fourier transformation as an operator and if the expression F[f(x)]=λf(y] constitutes an eigenproblem despite the different arguments of the function f.
  • Another participant asserts that it is indeed an eigenproblem but expresses uncertainty about the definition of "symmetric" being used.
  • A third participant reiterates the assertion that it is an eigenproblem and seeks clarification on the significance of the change in arguments from x to y, questioning if the mapping f(y) to f(x) represents a trivial isomorphism.

Areas of Agreement / Disagreement

Participants express differing views on the definitions and implications of symmetry and the nature of the operator, indicating that the discussion remains unresolved with multiple competing perspectives.

Contextual Notes

There is a lack of clarity regarding the definitions of symmetric and unitary operators, as well as the significance of the change in function arguments, which may affect the interpretation of the Fourier transformation as an eigenproblem.

LagrangeEuler
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I have two questions regarding Fourier transformation. First of all is it ok to call Fourier transformation operator, or it should be distinct more? For instance, if I wrote
F[f(x)]=\lambda f(y)
is that eigenproblem, regardless of the different argument of function ##f##? Could I call ##F## unitary operator if the transformation is symmetric?
 
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Office_Shredder said:
The answer is yes, it's an eigenproblem, and it's not clear what the definition of symmetric you are using is.

But it's probably worth looking at the definition of a unitary operator is
https://en.m.wikipedia.org/wiki/Unitary_operator
I asked it because the definition is
Af(x)=\lambda f(x)
same argument ##x##. And in my question is
Af(x)=\lambda f(y). Is there some reference where this is discussed?
 
Sorry, I missed the change in argument. Can you give some more context to your example? Like, how is the difference between x and y significant here? Is the map f(y) goes to f(x) a trivial isomorphism between functions of y and functions of x?
 

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