ss2tf give different results depending on version of MATLAB

I use Matlab version 8.2 and my friend 7.14 we get different result using this code

A=[0 1 0 0; -(1.19/1.7e-3) -((8.39e-3)/320)^2/(3.21*1.7e-3) (1.19/1.7e-3) 0; 0 0 0 1; (1.19/4.8e-3) 0 -(1.19/4.8e-3) 0];

B=[0;8.39e-3/(3.21*1.7e-3*320); 0; 0];

C=[0 1 0 0];

D=0;

[n,d]=ss2tf(A,B,C,D);

transfun = tf(n,d)

We get different transfer function and different variable n. Why is that?

Answer 1

[Craig]

Over releases algorthims are updated to improve reliability and accuracy of computations. As a result answers can differ between releases.