i need help to make mathlab code step 4 and step 5?

i have mathlab code about genetic algorithm ..

my mathlab code is only at the chromosome selection stage

pop_size = 5;
%sigma=0
%q=0
all_Evals = zeros(pop_size,1);
for count = 1:pop_size
   %fprintf('count =%d\n',count);
   c = [10 2 20 11
    12 7 9 20 
    4 14 16 18];
    [m,n] = size(c);
    phi = 1:m*n;
    s = [15
    25
    10
    ];
    d = [5 15 15 15];
    
    for count2=1:length(phi)
       % fprintf('count2=%d\n',count2);
        used_idx = randi(length(phi));
        trial = phi(used_idx);
        phi(used_idx) = [];
        i = [1+mod((trial-1),m)];
        j = [1+mod((trial-1),n)];
        x(i,j) = min(s(i),d(j));
        s(i) = s(i)-x(i,j);
        d(j) = d(j)-x(i,j);
     Eval=0;
     for j=1:n
         for i=1:m
            if x(i,j)>0
                Eval=Eval+c(i,j)*x(i,j);
               %fprintf('Eval=%d\n',Eval);
             end
         end
     end
    end
 disp(Eval)
 all_Evals(count) = Eval
end
 sum_of_Evals = sum(all_Evals)
 all_p=zeros(pop_size,1)
 for count=1:pop_size
 %probabilitas_eval = all_Evals(count)/sum_of_Evals
 %kumulatif_eval = cumsum(probabilitas_eval)
 p=(sum_of_Evals-all_Evals(count))/(sum_of_Evals*(pop_size-1))
 %fprintf('all_Evals(count)=%d\n',all_Evals(count));
 all_p(count)=p
 end
  kumulatif_eval=cumsum(all_p)
%all_p=zeros(pop_size,1)
all_roulate=zeros(pop_size,1);
%%newInd = x(i,j)
%r=rand()
for count=1:pop_size
    roulete = rand()
    all_roulate(count)= roulete
end

for a=1:pop_size
    for b=1:pop_size
        if   roulete <= kumulatif_eval(b)
            fprintf('kumulatif_eval(b)=%d\n',kumulatif_eval(b));
           x = b 
        end
    end
end

Step 4: Generate a random number roullate from range [0,1]

Step 5: if kumulatif_eval(b-1)< roulete<= kumulatif_eval(b) then choromosome X(b) is selected

can anyone help fix my mathlab code this? Please help