Fourier Transform, Optical Computing, Technology, Next Generation Tech.
involve N-1​ complex multiplications each (technically N​, but the first component of the vector ​c is 1​, so there is no need to perform the multiplication explicitly). This can be done with either ​4 (N-1) real multiplications and 2 (N-1)​ real additions, or ​3 (N-1)​real multiplications and ​