How to get the transfer function between any state and the control input from their state space representation?

If we have a system S in state space representation

 where A=

           x1       x2       x3       x4
   x1   -0.136   0.0235        0    -9.81
   x2  -0.1184   -1.828    223.6        0
   x3   0.3845  -0.5686   -1.219        0
   x4        0        0        1        0

and B =

           u1
   x1       0
   x2  -52.96
   x3  -312.3
   x4       0

 D and C are zero.

What code or syntax can i use to get the transfer function x4/u1 ??

[Nihar Deodhar]

the standard function is 'ss2tf'