Paper 3, Section I, D

Methods
Part IB, 2019

Define the discrete Fourier transform of a sequence {x0,x1,,xN1}\left\{x_{0}, x_{1}, \ldots, x_{N-1}\right\} of NN complex numbers.

Compute the discrete Fourier transform of the sequence

xn=1N(1+e2πin/N)N1 for n=0,,N1.x_{n}=\frac{1}{N}\left(1+e^{2 \pi i n / N}\right)^{N-1} \quad \text { for } n=0, \ldots, N-1 .