indexing for a single for loop of an upper triangular matrix

Hello everyone,

I had a question and was wondering if it is even possible. I want to create a square matrix using some comparison function. The matrix is symmetric by nature of this function. I want to write the comparisons using a single for loop but only want the for loop to use the indices of an upper triangular matrix. How would I do this in matlab? Thank you in advance.

Answer 1

[Matt J]

If U is the upper-triangular matrix,

      Iset=nonzeros(triu( reshape(1:numel(U), size(U)) ));

      for i=Iset

        ....

      end