M=26;N=32;n=0M; xa=0floorM2+1; xb= ceilM2-11; xn=xaxb; Xk=fftxn1024; X32k=fftxn32; x32n=ifftX32k; X16k=X32k12N; x16n=ifftX16kN2; subplot322;stemnxn;box on titleb 三角波序列xn;xlabeln;ylabelxn;axis0320

M=26;N=32;n=0:M; xa=(0:floor(M/2))+1; xb= ceil(M/2):-1:1; xn=[xa,xb]; Xk=fft(xn,1024); X32k=fft(xn,32); x32n=ifft(X32k); X16k=X32k(1:2:N); x16n=ifft(X16k,N/2); subplot(3,2,2);stem(n,xn,'.');box on title('(b) 方波序列x(n)');xlabel('n');ylabel('x(n)');axis([0,32,0,20]) k=0:1023;wk=2k/1024; subplot(3,2,1);plot(wk,abs(Xk));title('(a)FT[x(n)]'); xlabel('\omega/\pi');ylabel('|X(e^j^\omega)|');axis([0,1,0,200]) k=0:N/2-1; subplot(3,2,3);stem(k,abs(X16k),'.');box on title('(c) 16点频域采样'); xlabel('k');ylabel('|X_1_6(k)|');axis([0,8,0,200]) n1=0:N/2-1; subplot(3,2,4);stem(n1,x16n,'.');box on title('(d) 16点IDFT[X_1_6(k)]'); xlabel('n');ylabel('x_1_6(n)');axis([0,32,0,20]) k=0:N-1; subplot(3,2,5);stem(k,abs(X32k),'.');box on title('(e) 32点频域采样'); xlabel('k');ylabel('|X_3_2(k)|');axis([0,16,0,200]) n1=0:N-1; subplot(3,2,6);stem(n1,x32n,'.');box on title('(f) 32 IDFT [X_3_2(k)]'); xlabel('n');ylabel('x_3_2(n)');axis([0,32,0,20]) M=26;N=64;n=0:M; xa=(0:floor(M/2))+1; xb= ceil(M/2):-1:1; xn=[xa,xb]; Xk=fft(xn,1024); X64k=fft(xn,64) ; x64n=ifft(X64k); X8k=X64k(1:8:N); x8n=ifft(X8k,N/8); subplot(3,2,2);stem(n,xn,'.');box on title('(b) 方波序列x(n)');xlabel('n');ylabel('x(n)');axis([0,32,0,20]) k=0:1023;wk=2k/1024; subplot(3,2,1);plot(wk,abs(Xk));title('(a)FT[x(n)]'); xlabel('\omega/\pi');ylabel('|X(e^j^\omega)|');axis([0,1,0,200]) k=0:N/8-1; subplot(3,2,3);stem(k,abs(X8k),'.');box on title('(c) 8点频域采样');xlabel('k');ylabel('|X_8(k)|');axis([0,4,0,200]) n1=0:N/8-1; subplot(3,2,4);stem(n1,x8n,'.');box on title('(d) 8点IDFT[X_8(k)]'); xlabel('n');ylabel('x_8(n)');axis([0,32,0,40]) k=0:N-1; subplot(3,2,5);stem(k,abs(X64k),'.');box on title('(e) 64点频域采样'); xlabel('k');ylabel('|X_6_4(k)|');axis([0,32,0,200]) n1=0:N-1; subplot(3,2,6);stem(n1,x64n,'.');box on title('(f) 64点IDFT[X_6_4(k)]'); xlabel('n');ylabel('x_6_4(n)');axis([0,64,0,20]