q=8;
p=8;
n=[0:1:15];y=exp(-((n-p).^2)/q);
subplot(2,1,1);stem(y(1:16));title('noise time domain signal');
Y=fft(y,16);
magY=abs(Y(1:1:9));
k=0:1:8;w=2*pi/16*k;
subplot(2,1,2);plot(w/pi,magY),title('power spectral density'),
xlabel('frequency(pi)')