How to calculate threshold for matrix in Matlab?

I wrote these codes to calculate a threshold for distance values between features of the dataset. after computing hamming distance (a) between columns of the dataset, I defined z value, when the distance between two features is more than z, (for example feature ith and jth) so the threshold is between i and j, and we can select the features based on this threshold and remove the rest of the features. At the end, I used fprintf to show the ith and jth features in the output.

I'll be very grateful to have your opinions how to improve the program to compute the threshold for selecting features. Thanks

close all;
clc
load lung.mat
data=lung; 
[n,m]=size(data);
l=1;
t=1;
data1=[];
data2=[]; 
    if data(i,m)==1
        data1(l,:)=data(i,:);
        l=l+1;
    else
        data2(t,:)=data(i,:); 
        t=t+1;
    end
end
if t>l
    data1(l:t-1,:)=0;
else
    data2(t:l-1,:)=0;
end
for i=1: m                       
  thisCol1=data1(:,i);      
  thisCol2=data2(:,i);
  a(i)=fHammingDist(thisCol1,thisCol2);
  z=sum(a)/m;
  if abs(a(i)-a(j))> z
      fprintf(' threshold is between %10.6f and %10.6f ',i,j);
  end
end
end

but there is an error for line

if abs(a (i)-a(j)) > z

Subscript indices must either be real positive integers or logicals.

Answer 1

[KALYAN ACHARJYA]

j define?

abs(a(i)-a(j))> z
%..........^

a5?

z=sum(a5)/m;
%.....^

[phdcomputer Eng]

i and j are counters for passing the array (a). I wanted to compare the values of this array with each other and if the distance between them is more than z so I want to save the indexes of the array ( i and j).

[KALYAN ACHARJYA]

Sir, I am asking have you define j and a5 in the code? When I checked, I didnot get it.

[phdcomputer Eng]

I didn't define j in the code, I don't know how to define the counter for passsing an array.

a5 is a typing mistake I meant a.

a(i)=fHammingDist(thisCol1,thisCol2);

a is an array that includes distances between columns of the dataset.

[KALYAN ACHARJYA]

Please do share

>>whos data

and

>>whos a 

Also What does it mean "define the counter for passsing an array"?