There are undefined variables in your code.
n=5;
row1 = 1:n;
col1 = (n+1):(2*n-1);
% Create the full-rank Hankel matrix of size n^2
H_full = hankel(row1, col1);
H_full is not of size nxn, as col1 has n-1 elements. If you want H_full of size nxn, change
col1 = (n+1):(2*n);
Getting indices of anti-diagonals
z=rot90(reshape(1:n^2,n,n));
%Antidiagonals
ind=[2 4];
%ctr=min(ind,2*n-ind);
omega=cell(1,numel(ind));
for k=1:numel(ind)
[r,c]=ind2sub([n n],diag(z,ind(k)-n));
omega{1,k}=[r c];
end
omega{1}
omega{2}
