# Thread: Arbitrary Symbols in MATLAB

1. ## Arbitrary Symbols in MATLAB

Hello Everyone!

I've doing some MATLAB recently, specifically in signal analysis applications specifically transfer functions.
I'm using the tf function as follows:
Code:
tf('s');
H = (s+1)/(s^2+2*s+2);
Now this is working fine, what if I want to use arbitrary constants like we do in dsolve function. What do we do then?
I essentially want to add transfer functions like:
Code:
H1 = (s+1)/(s^2+2*s+2);
H2 = (a*s+b)/(s^2+2*s+2); % a and b are arbitrary constants
H = H1 + H2

2. Originally Posted by rebghb
Hello Everyone!

I've doing some MATLAB recently, specifically in signal analysis applications specifically transfer functions.
I'm using the tf function as follows:
Code:
tf('s');
H = (s+1)/(s^2+2*s+2);
Now this is working fine, what if I want to use arbitrary constants like we do in dsolve function. What do we do then?
I essentially want to add transfer functions like:
Code:
H1 = (s+1)/(s^2+2*s+2);
H2 = (a*s+b)/(s^2+2*s+2); % a and b are arbitrary constants
H = H1 + H2
What happens when you type the above at the console?

(I would expect them to default to symbolic objects, if they don't try declaring them as such)

CB

3. Exactly! How do I declare them as such?