Fractional Fourier transform
In mathematics, in the area of harmonic analysis, the fractional Fourier transform (FRFT) is a family of linear transformations generalizing the Fourier transform. It can be thought of as the Fourier transform to the nth power, where n need not be an integer – thus, it can transform a function to any intermediate domain between time and frequency.
Source: Wikipedia — Fractional Fourier transform (CC BY-SA 4.0)