I try to design filter by using The mutation operator(One of the operation in genetic algorithm)

% parameter using in mutation operator
N=100 %population size
m=0.01 %mutation rate

% filter information
f = [0 0.3 0.4 0.6 0.7 1];
a = [0 0.0 1.0 1.0 0.0 0];
b = firpm(17,f,a);

A simple way to achieve mutation would be to randomly generate chromosomes, if the chromosome is b (the vector of coefficient) ,how can i apply randomly generate in matlab ?

Thank you in advance.