I tried to optimize distance matrix that construct phylogenetic tree by differential evolution algorithm and i need to sure about my implementation and this is my code about that , please anyone can help me

function [working_distance_after_50_itr] = working_distance_Matrix()

n = 5; %number of species

u = importdata('original distance.txt');

d = u(~~tril(u));

t = importdata('initial working distance.txt'); x = t(~~tril(t));

itr=input('Enter no. of generations: ');

F = 0.01; %Mutation factor

for j = 1 : itr

for i = 1 : length(x)

%y = x;

b = x(i);

s = setdiff(x,b);

r1 = s(randi(numel(s),1,1));

b = [x(i),r1];

s = setdiff(x,b);

r2 = s(randi(numel(s),1,1));

%b = [x(i),r1,r2];

%s = setdiff(x,b);

%r3 = s(randi(numel(s),1,1));

c(i) = x(i) + (F * (r1 - r2)); %Mutant vector

end

if fitness(c)>= fitness(x) %selection step

x = c;

end

end

g = tril(ones(n),-1);

g(~~g)=x;

working_distance_after_50_itr =tril(g,-1)+tril(g)';

function fitness_value = fitness(N)%fitness function

for k = 1 : length(N)

r(k)=((N(k)- d(k))/d(k))^2;

end

z = sum(r);

a = (n*(n-1))/2;

h = 1/(a-1);

fitness_value = 1/(100 * sqrt(h*z));

end

end