DSP调用.rar_shiyanbaogao_sickczg

N = 8;n = 0:N-1; x4n = cos(pi*n/4); x5n = cos(pi*n/4)+cos(pi*n/8); X4k8 = fft(x4n); X5k8 = fft(x5n); N = 16;n = 0:N-1; x4n = cos(pi*n/4); x5n = cos(pi*n/4)+cos(pi*n/8); X4k16 = fft(x4n); X5k16 = fft(x5n); subplot(2,2,1);stem(abs(X4k8)); title('(a)8点DFT[x_4(n)]'); xlabel('ω/π');ylabel('幅度'); axis([0,7,0,1.2*max(abs(X4k8))]); subplot(2,2,2);stem(abs(X5k8)); title('(a)8点DFT[x_5(n)]'); xlabel('ω/π');ylabel('幅度'); axis([0,7,0,1.2*max(abs(X5k8))]); subplot(2,2,3);stem(abs(X4k16)); title('(b)16点DFT[x_4(n)]'); xlabel('ω/π');ylabel('幅度'); axis([0,15,0,1.2*max(abs(X4k16))]); subplot(2,2,4);stem(abs(X5k16)); title('(b)16点DFT[x_5(n)]'); xlabel('ω/π');ylabel('幅度'); axis([0,15,0,1.2*max(abs(X5k16))]);