Spectral set

In mathematics, particularly in the field of harmonic analysis and number theory, a **spectral set** refers to a set of integers that has properties related to the Fourier transform and the theory of sets of integers in relation to frequencies. The precise definition of a spectral set can depend on the context in which it is being used, but a common way to define a spectral set is in relation to its ability to be represented as a set of frequencies of a function or a sequence.