# MATLab help?

Discussion in 'Math' started by srinath.msd, Jan 24, 2014.

1. ### srinath.msd Thread Starter New Member

Sep 19, 2011
5
0
hey guys..
i need to compute the mathematical model of a transfer function using simulink in matlab.. however i first have to convert it into a state space model.. need some help with this one as i dont know state space modeling very well...

the transfer function is:

25.04s + 2.008/s^3 + 5.0325s^2 + 25.1026s + 5.008

2. ### t_n_k AAC Fanatic!

Mar 6, 2009
5,448
784
Your transfer function seems to have two terms in 's'. Are you sure you've transcribed it correctly?

You don't know state-space modelling. Time to do some self-study.

3. ### Georacer Moderator

Nov 25, 2009
5,151
1,266
Actually, Matlab allows for not studying in this case, if you are specific enough.

Given a transfer function
$G(s)=\frac{A(s)}{B(s)}$

you can insert it into Matlab and create an LTI system block out of it by typing:
Code ( (Unknown Language)):
1. G=tf([an ... a2 a1 a0],[bm ... b2 b1 b0])
Then, you can convert this TF into a space-state system with
Code ( (Unknown Language)):
1. G1=ss(G)
The opposite is true as well:
Code ( (Unknown Language)):
1. G2=tf(G1)
Here are some references:
http://www.mathworks.com/help/control/ref/tf.html
http://www.mathworks.com/help/control/ref/ss.html