Filtering Perspective of the Zero-State Response
Use the MATLAB filter command to compute and sketch the zero-state response for the system described by \left(E^2+0.5 E-1\right) y[n]=\left(2 E^2+6 E\right) x[n] and the input x[n]=4^{-n} u[n] .
We solve this problem using the same approach as Ex. 3.19. Although the input is bounded and quickly decays to zero, the system itself is unstable and an unbounded output results.
>> n = (0:11); x = @(n) 4.^(-n).*(n>=0);
>> a = [1 0.5 -1]; b = [2 6 0]; y = filter(b,a,x(n));
>> clf; stem(n,y,’k’); xlabel(’n’); ylabel(’y[n]’); axis([-0.5 11.5 -20 25]);