Anallytical function in COMSOL

Hi Ivar,

I have a difficulty defining an analytical funcyion as a function of frequency. the frequency is going to sweep so the function should sweep too.
I have the following form for my function.

E which is function of frequency ----> E(freq) and then the optical property of my material as

Eps = A(E) + B(E)+ C(E) + D(E) +F(E)
. where A,B,C,D and F are lengthy functions. I can only define one expression per function. and if the expression is implicitly function of frequency ( each expression is function of E and E is function of frequency) then it wont sweep when frequency sweeps.

I appreciate if you can kindly provide me a clue.

Kind Regards,
Yasaman