Matlab函教 example3_11 k=5:15; xk=zeros(1, 21); subplot(3, 1, 2), stem(k, abs(xk1)) n=5:15 grid on xk(1)=2;xk(3)=1 %X2(k) ·xk(9)=1;xk(11)=2; subplot(3, 1, 1), stem(n, xk) n=0:7 grid on X=2*coS (3*pin/4)-4sin(3 *pi*n/4); %X1(k) ●fork=5:15 n=0:15; p=k+6 . X2*cos(3*pi*/8)+4*sin(5*pi*n/8); xk2(p)=0; for k-5: 15 p=k+6; n=0:7; xk1(p)=0; xk2(p=mean(x*exp(*pi**n/4)); n=0:15; end xk1(p)=mean(x *exp( k=5:15; jpi*k*n/8)) end subplot(3, 1, 3), stem(k, abs(xk2)) grid onMatlab函数 ⚫ % example3_11 ⚫ xk=zeros(1,21); ⚫ n=-5:15; ⚫ xk(1)=2;xk(3)=1; ⚫ xk(9)=1;xk(11)=2; ⚫ subplot(3,1,1),stem(n,xk) ⚫ grid on ⚫ % X1(k) ⚫ n=0:15; ⚫ x=2*cos(3*pi*n/8)+4*sin(5*pi*n/8); ⚫ for k=-5:15 ⚫ p=k+6; ⚫ xk1(p)=0; ⚫ n=0:15; ⚫ xk1(p)=mean(x.*exp(- j*pi*k*n/8)); ⚫ end ⚫ k=-5:15; ⚫ subplot(3,1,2),stem(k,abs(xk1)) ⚫ grid on ⚫ % X2(k) ⚫ n=0:7; ⚫ x=2*cos(3*pi*n/4)-4*sin(3*pi*n/4); ⚫ for k=-5:15 ⚫ p=k+6; ⚫ xk2(p)=0; ⚫ n=0:7; ⚫ xk2(p)=mean(x.*exp(-j*pi*k*n/4)); ⚫ end ⚫ k=-5:15; ⚫ subplot(3,1,3),stem(k,abs(xk2)) ⚫ grid on