t=[1:64]*2*pi/7;
% this gives a frequency that is not one of the FFT freqs
x=exp(i*t);
y=fft(x);
plot(2*log(abs(y)));
title('Periodogram of X with N=64');
xlabel('Frequency index j;  lambda_j = 2*pi*j/N');
ylabel('LOG_10(ABS(Y^2))');
gtext('X = exp(i*[1:64]*2*pi/7)');
% print -deps pgram0a