Fourier Transform, Optical Computing, Free Space Optics.
matrix into ​4 sub-matrices as follows: The next step is to perform the 2D FT of each sub-matrix: For larger matrices, one would need to exchange the line j of each sub-matrix with the line nx +1- j for each j between 2 and nx. For nx=2, this is not needed (it would only exchange line ​2 with