example3_12a.m

西交大刘树棠写的《数字信号处理》那本书的所有源代码

n=[0:1:99];x=cos(0.48*pi*n)+cos(0.52*pi*n);
n1=[0:1:9];x1=x(1:1:10);
subplot(2,2,1);stem(n1,x1);title('signal 0<=n<=9');
axis([0,10,-2.5,2.5]);
X1=dft(x1,10);
magX1=abs(X1(1:6));
k1=0:1:5;
w1=2*pi*k1/10;
subplot(2,2,2);stem(w1/pi,magX1);
title('DFT');
n2=n;x2=[x(1:1:10),zeros(1,90)];
subplot(2,2,3);stem(n2,x2);title('signal+0');
X2=dft(x2,100);
magX2=abs(X2(1:1:51));
k2=0:1:50;w2=2*pi/100*k2;
subplot(2,2,4);stem(w2/pi,magX2);title('DFT');
axis([0,1,0,10]);