//Example 7.5 clc; syms Wo n z; x1=exp(sqrt(-1)*Wo*n); X1=symsum(x1*(z^-n),n,0,%inf); x2=exp(-sqrt(-1)*Wo*n); X2=symsum(x2*(z^-n),n,0,%inf); X=(X1+X2)/2; disp(X,'X(z)=');