how to make cumsum in ascending order of values

I have a matrix

A = [1 2 4 7; 
     2 3 1 6; 
     4 5 6 15]

. The last column is sum of rows

I want to make another column on right side displaying cumulative sums of last column in ascending order of the forth column (row sums). The result of last column shall be as follows:--

[22 28  15]

So, final matrix will become

[1 2 4 7  22; 
 2 3 1 6  28; 
 4 5 6 15 15].

Answer 1

[Image Analyst]

I'm not quite following how your description gives you the result, but I followed your written directions and got this:

A = [1 2 4 7; ...
     2 3 1 6; ...
     4 5 6 15]
% Sort last column in ascending order:
rightColumn = sort(A(:, end), 'ascend')
% Get the cumulative sums of that
c = cumsum(rightColumn);
% Append onto right edge of A as a new column.
A = [A, c]