function [Xk] = dfs(xn,N)
% Computes Discrete Fourier Series Coefficients
% ---------------------------------------------
% [Xk] = dfs(xn,N)
% Xk = DFS coeff. array over 0 <= k <= N-1
% xn = One period of periodic signal over 0 <= n <= N-1
%  N = Fundamental period of xn
%
n = [0:1:N-1];                       % row vector for n
k = [0:1:N-1];                       % row vecor for k
WN = exp(-j*2*pi/N);                 % Wn factor
nk = n'*k;                           % creates a N by N matrix of nk values
WNnk = WN .^ nk;                     % DFS matrix
Xk = xn * WNnk;                      % row vector for DFS coefficients