Specifications

3 Operations on LTI Models
3-10
adds a second input to the state-space model sys by appending the B and D
matrices. You should simultaneously modify both matrices with a single
set
command. Indeed, the statements
sys.b = [b1 b2]
and
set(sys,'b',[b1 b2])
cause an error because they create invalid intermediate models in which the B
and D matrices have inconsistent column dimensions.