Fourier Transform, Optical Computing, Free Space Optics.
(9,9,9,9,9,9,9,9,9)​: You can check that the result is correct (the FT of a uniform array has just one non-vanishing coefficient, which is the sum of the input coefficients). Finally, let us do a check with a 100 by 100 random matrix. It would, of course, be quite cumbersome to check the result by