Am unable to wrap my head on this question regarding for loop , can someone explain the question and maybe write the code please.

[Walter Roberson]

A number of solutions have been posted already; search for halfsum

Answer 1

[Awais Saeed]

Why use a loop if it can be done without it

A = [1 2 3; 4 5 6; 7 8 9];
[sum_of_elements] = halfsum(A)

sum_of_elements = 26

function [sum_of_elements] = halfsum(M)
    A = M;
    sum_of_elements = sum(triu(A), 'all');
end

[Dawud Adam Rabiu]

Sorry the question requires you to use for loops(nested) as the grader doesnt support the function triu

[Awais Saeed]

just replace with this function

function [sum_of_elements] = halfsum(M)
    A = M;                      % your original matrix
    B = zeros(size(A));         % create a matrix of size A for future use
    for row = 1:1:size(A,1)     % loop through all rows
        for col = row:1:size(A,2)   % columns must be equal to row
            B(row,col) = A(row,col) % pick elements from A to put them in B
        end
    end
    sum_of_elements = sum(B,'all')  % take sum of all elements
end

[Dawud Adam Rabiu]

Thank you Awais, can you explain the lines of code please ?

[Awais Saeed]

I have added some comments. For better understanding use debug mode.