MATLAB: Help in adding a descending order a symetric matric

descend order

Hello! I want to put in a descending order just the part upper the main diagonal in a symmetric matrix and to get the index of those elements. What should I change in this code?
function [values,i,j] = max(A,n)
[a, linIdx] = sort(A(:),'descend');
values = a(1:n);
[i,j] = ind2sub(size(A),linIdx(1:n));

Best Answer

Hello,
Here's a very inelegant solution, but it does the job. I'm making all values below the main diagonal -Inf so that they're guaranteed to not be apart of the a(1:n) when you sort, assuming your original matrix does not contain -Infinities (this also includes the main diagonal, I can change it to exclude it if necessary).
function [values,i,j] = whateveryouwanttocallit(A,n) 
   low = tril(A-Inf,-1)+1;
   A = low.*A;
   [a, linIdx] = sort(A(:),'descend');
   values = a(1:n);
   [i,j] = ind2sub(size(A),linIdx(1:n));
end
Hope this helps!
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