function [t,imp] = train(T,N)

% Function [T,IMP] = TRAIN(T,N) creates a Fourier series approximation to a 
% train of impulses with period T using N harmonic terms each side of zero.
% Three periods of the function are generated.

ws = (2*pi)/T;  % Sampling frequency in rad/s

t = [0:0.001*T:3*T]';  % Create a column time vector over 3 periods with 1000 points/period

imp = zeros(length(t),1);  % Dummy array to hold impulse train

for n = -N:N    % FOR loop over the number of coefficients
    imp = imp + real(exp(j*n*ws*t));  % Ignore imag part (should be zero anyway)
end;