How to compute transfer functions between an input and an output point?

I created a state-space model using "ss" and matrices A, B, C and D:

sys = ss(A,B,C,D);

My state vector "z" is composed by 315 velocities and 315 displacement, so its derivative is composed by 315 accelerations and 315 velocities. Since the outputs "y" that I need are the accelerations, I defined C and D as follows:

C = A(1:315,:);
D = B(1:315,:);

If, for example, I want to compute the transfer function between a certain input point and a certain output point, I write:

[mag,phase] = bode(sys(out_point,in_point),2*pi*f);

where "f" is the frequency vector that I set. Is this correct? Because I need these transfer functions to perform other calculations afterwards and the results I get from these calculations are not what I expected.

[Yuvaraj Venkataswamy]

Try this,

https://in.mathworks.com/help/ident/ref/tfest.html

[Donato Foggetti]

Did you at least read the question? Because I cannot see any realtionship between what I asked and what you answered. Looks like you read "transfer funcion" in the title and answered with a MATLAB "doc".

If the relationship exists, can you please explain me how it works?

Thank you in advance.