% Chapter 3 : Example 3.21%             Reconstruction using the stairs and plot functions%figure(1); clf% Discrete-time Signal x1(n) : Ts = 0.0002Ts = 0.0002; n = -25:1:25; nTs = n*Ts;x = exp(-1000*abs(nTs));% Analog Signal reconstruction using stairssubplot(2,1,1); stairs(nTs*1000,x);xlabel('t in msec.'); ylabel('xa(t)')title('Reconstructed Signal from x1(n) using zero-order-hold'); hold onstem(n*Ts*1000,x); hold off%% Analog Signal reconstruction using plotsubplot(2,1,2); plot(nTs*1000,x);xlabel('t in msec.'); ylabel('xa(t)')title('Reconstructed Signal from x1(n) using first-order-hold'); hold onstem(n*Ts*1000,x); hold off