Hi! I have a little problem. I have an exercise where it's said that the tranfer function gives 3 poles and the rank of the controllability matrix is 4. The question are: how many state has the sistem? Is it controllable? Is it observable? My solution were...the number of state is at least 4. If it's of 4th order, then it's controllable, but not observable. If is of higher order....no idea!!!!