N=12;w1=2*pi/N;k=0:N-1;
x=[1,2,3,4,5,6,6,5,4,3,2,1];
X=dft(x,N);
magX=abs(X),phaX=angle(X)*180/pi
subplot(2,1,1);
axis([-0.1,12.1,0,50]);
hold on
stem(k,magX);
ylabel('|x(k)|');title('DFT的幅度:N=12');
hold off
subplot(2,1,2);
axis([-0.1,12.1,-400,400]);
hold on
stem(k,phaX);
ylabel('度');title('DFT的相角:N=12');