This paper concerns the structure that can be achieved by feedbacl< in descriptoi
systems without controllability at infinity.
Ex = Ax + Bu
y = Cx
With system matrices EeC^",As C''",BE ^ C""^, state x = x(t)EC", input
u = u(t)e C". The following that answers the question of when state feedback may be
used to make a descriptor system reguler
