2=fft(x2,N);Рsubplot(4,1,1);stem(n1,x1,'.');Рxlabel('n1');ylabel('x1');title('短长度信号');Рsubplot(4,1,2);stem(wk,abs(xk1),'.');Рxlabel('wk');ylabel('幅度');title('点信号的64点dft的幅频特性');Рsubplot(4,1,3);stem(n2,x2,'.');Рxlabel('n2');ylabel('x2');title('长长度信号');Рsubplot(4,1,4);stem(wk,abs(xk2),'.');Рxlabel('wk');ylabel('幅度');title('?长信号的64点dft的幅频特性');Р图形Р整周期截取РN=64;Рk=0:N-1;Рwk=2*k/N;Рw=pi/4;Рn1=[0:N];Рx1=sin(w*n1);Рxk1=fft(x1,N);Рn2=[0:40];Рx2=sin(w*n2);Рxk2=fft(x2,N);Рsubplot(4,1,1);stem(n1,x1,'.');Рxlabel('n1');ylabel('x1');title('整周期截取信号');Рsubplot(4,1,2);stem(wk,abs(xk1),'.');Рxlabel('wk');ylabel('幅度');title('整周期的64点dft的幅频特性');Рsubplot(4,1,3);stem(n2,x2,'.');Рxlabel('n2');ylabel('x2');title('非整周期截取信号');Рsubplot(4,1,4);stem(wk,abs(xk2),'.');Рxlabel('wk');ylabel('幅度');title('·费整周期的64点dft的幅频特性');Р图形