How to find the first 3 roots of a nonlinear single variable equation?

The problem I am trying to solve includes 5 constants and one variable. Due to my variable "gamma" I obtain different w values as solution. However, I am getting the first root, I need to get two more. Here is the code that I wrote so far.

E=2*10^9;

A=2^2*pi*10^-6;

rho=1000;

L=0.1;

mpoint=0.1;

dummy=1;

syms w

for gamma=0:0.01:pi

beta=L*w*sqrt(rho/E);

R1=mpoint*w*sin(beta)*exp(1i*gamma)/(A*sqrt(rho*E));

R2=exp(2i*gamma)-2*co(beta)*exp(1i*gamma)+1;

f(dummy)=R1+R2;

kokler(dummy)=solve(f(dummy),w);

dummy=dummy+1;

end

plot(kokler,gamma)

My main target is to obtain dispersion plot(gamma vs. w) to indicate the band gap in between the branches.