Sort matrix to get the row and column position of sorted matrix

how should i sort the matrix

M = [0,15,14,13,10,7,4,1,2;
0,0,9,6,4,12,1,3,1;
0,0,0,10,8,5,3,1,2;
0,0,0,0,17,2,11,1,4;
0,0,0,0,0,1,12,1,7;
0,0,0,0,0,0,1,7,5;
0,0,0,0,0,0,0,3,9;
0,0,0,0,0,0,0,0,8];

to get the sorted index positions as

[4,5], [1,2], [1,3], [1,4], [2,6], [5,7], [4,7], [1,5].....

Answer 1

[Ameer Hamza]

[~,idx] = sort(M(:), 'descend');
idx(M(:)==0) = [];
[row, col] = ind2sub(size(M), idx);
indexes = [row col];

Result:

indexes =

     4     5
     1     2
     1     3
     1     4
     2     6
     5     7
     4     7
     3     4
     1     5
     .......