Give an example of a non-zero function $ f ∈ L^2 ( Z (2))$ such that $Ff=−f$. This is an eigenvector corresponding to the eigenvalue−1.)
I am extremely bad at questions like this and would love to have a better understanding or maybe suggestions on how to learn how to answer questions like this.
This question is asking what non-zero function gets the opposite of the function when you take the Fourier transform