MATLAB: How to use “eig” in symbolic variables

Question

How can I use "eig" in symbolic variables?

I have this Equation : [A]*{x}=(omega)^2*[B]*{x}

which A=[2a+3b ,2b+3a ; a+b,a-b] And B=[5a+8b, b^2+5 ; a-5b,2b+3a]

and want to use "eig" for it.

Answer 1

syms a b l
A=[2*a+3*b ,2*b+3*a ; a+b,a-b] ; 
B=[5*a+8*b, b^2+5 ; a-5*b,2*b+3*a] ; 
C = A-l^2*B ;
eqn= det(C)==0 ;
iwant = solve(eqn,l)