A discrete-time system is implemented by MATLAB function y=ltiwhich(x).
(a) Determine whether the system is linear and time-invariant. Hint: You can check the response to the input x[n] = (-1)nu[n]. Why?
(b) If the system is LTI determine its impulse response h[n] and its frequency response H (ejω) using MATLAB.
(c) Estimate |H (ejω)| and ∠H (ejω) using (5.14) for ω = kπ/10, 0 ≤ k ≤ 10 and compare with the results obtained in (b).