>> n=1

n =

     1

>> Gp=tf([1/n],[1 1 1 n/2],'inputdelay',2*n)
 
Transfer function:
                     1
exp(-2*s) * -------------------
            s^3 + s^2 + s + 0.5
 
>> [q,p]=pade(2*n,1)

q =

    -1     1


p =

     1     1

>> Gpade_1=tf(q,p)
 
Transfer function:
-s + 1
------
s + 1
 
>> [q,p]=pade(2*n,2)

q =

     1    -3     3


p =

     1     3     3

>> Gpade_2=tf(q,p)
 
Transfer function:
s^2 - 3 s + 3
-------------
s^2 + 3 s + 3
 
>> [q,p]=pade(2*n,3)

q =

    -1     6   -15    15


p =

     1     6    15    15

>> Gpade_3=tf(q,p)
 
Transfer function:
-s^3 + 6 s^2 - 15 s + 15
------------------------
s^3 + 6 s^2 + 15 s + 15
 
>> G=tf([1/n],[1 1 1 n/2])
 
Transfer function:
         1
-------------------
s^3 + s^2 + s + 0.5
 
>> Gp_approx3=G*Gpade_3
 
Transfer function:
               -s^3 + 6 s^2 - 15 s + 15
-------------------------------------------------------
s^6 + 7 s^5 + 22 s^4 + 36.5 s^3 + 33 s^2 + 22.5 s + 7.5
 
>> sisotool(Gp_approx3)