Graduate Is this Fourier transformation an eigenproblem?

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SUMMARY

The discussion centers on the classification of the Fourier transformation as an eigenproblem and the nature of the operator involved. It is established that the Fourier transformation can indeed be considered an eigenproblem, even when the function arguments differ, as indicated by the equation F[f(x)]=λ f(y). Furthermore, the transformation qualifies as a unitary operator if it maintains symmetry, although the definition of symmetry requires clarification. The conversation emphasizes the importance of understanding the distinction between the arguments of the function in the context of eigenvalue problems.

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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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