Closed loop properties

--> spec(pr(2))
 ans  =
! - 10.003858              !
! - 9.9999983 + 0.0038563i !
! - 9.9999983 - 0.0038563i !
! - 9.9961453              !
! - 10.                    !
! - 9.9999997              !
! - 10.                    !
! - 9.9999997              !
--> //frequency analysis
--> // black(pr,0.01,100,['position','theta'])
--> g_margin(pr(1,1))
 ans  =
   Inf

-->//transfer matrix representation
--> hr=clean(ss2tf(pr),1.d-10)
 hr  =
!                             2     !
!     - 47.853659 + 0.9756098s      !
!   ------------------------------  !
!                       2     3   4 !
!   10000 + 4000s + 600s + 40s + s  !
!                                   !
!                       2           !
!           - 4.8780488s            !
!   ------------------------------  !
!                       2     3   4 !
!   10000 + 4000s + 600s + 40s + s  !