Fourier Transform, Optical Computing, Free Space Optics.
several tens of entries), you have an efficient way to do the ‘small’ 2D FTs. Indeed, when using this algorithm to compute ​N one-dimensional FTs of size N​, you need ​2N smaller 2D ones and a number ​O(N²) of other operations. If each of the smaller transforms can be done sufficiently fast (and