Simulink Bode plot

DianeS

Greetings eveyone!

I'm having a little trouble with this program. I know i can get the Bode plot of a transfer function written in MATLAB, but i have a very very large transfer function. So my question is: can you get the BODE plot of a simulink block diagram?

I've done some research about it.
1.
>>[A,B,C,D]=linmod('my_model');
>>sys=ss(A,B,C,D)
>>bode(sys)
When you do this, do you need to establish input and output points (linearization points) in your simulink model? or what does it take for reference?

2.
Establishing linearization points and use Tools>Control Design> Linear analysis> Bode plot

Is there a better approach? Like i said i have a very large system.
Thanks in advance for your reading and comments.

Diane.