Source: wikibot/plancherel-theorem
= Plancherel theorem
{wiki=Plancherel_theorem}
The Plancherel theorem is a fundamental result in the field of harmonic analysis, particularly in the context of Fourier transforms and Fourier series. It establishes an important relationship between the \\( L^2 \\) spaces of functions and distributions, indicating that the Fourier transform is an isometry on these spaces.