function square_fourier (n)
% generate fourier series for a square wave, up to n terms, on points t.
t = 0 : 0.001 : 1;
T = 1;
F = zeros (size (t));
for k = 1 : 2 : (2*n-1)
    F = F + sin (2*pi*k .* t ./ T) ./ k;
end
F = (4/pi) .* F;
plot (t, F)