%  Example 8.11
% second order response
%  poles are -1 + 4j and -1 - 4j
num = 17; den = [1 2 17];
t = 0:10/300:10;
y = step(num,den,t);
env = 1-sqrt(17)/4*exp(-t);
plot(t,y,t,env,'--');
xlabel('Time (sec)')
ylabel('y(t)')
title('Second order step response')
