Eliminate repetition in rows addition

Hi,

How to eliminate repetitions that happen in this rows addition? I am adding the numbers in row 1 and 2, row 1 and 3 and row 2 and 3.

The matrix is:

A =

3 10

5 6

7 8

And after running this code this is what I get:

B =

26 24 28

24 22 26

28 26 30

How to make it more efficient, since I do not need to repeat the same addition (i.e. row 2 and 1) and self addition (row 1 and 1). I should get B like this:

B =

0 24 28

0 0 26

0 0 0

Any idea?

A = [3 10; 5 6; 7 8];

    for i = 1:3
        for j = 1:3
                      
        Ai = A(i,:);
        Aj = A(j,:);
       
        result = 0;
      
            for k = 1:2
           
            result = result + Ai(k) + Aj(k);
    
            end
            
    B(i,j) = result;
              
        end
    end

    B

Answer 1

[Adam Danz]

You can replace those loops with this:

A = [3 10; 5 6; 7 8];
triu(sum(A,2)+sum(A,2)',1)
ans =
     0    24    28
     0     0    26
     0     0     0             

If you want to retain the diagonal,

triu(sum(A,2)+sum(A,2)')
ans =
    26    24    28
     0    22    26
     0     0    30