Fourier Transform, Optical Computing, Free Space Optics.
see how the second algorithm works on a practical example. Assume one wants to compute the FTs of the arrays (1,1,1,1), (1,1,1,0), (1,1,0,0), and (1,0,0,0) using a device which can only take arrays with shape (2,2) as inputs. First batch the 4 inputs in a matrix (one per line): Then separate this