concatenate a vector in column-major order

I am trying to solve a problem where the elements of a vector is compared to something and if found true the location of the element (say(1,2)) is output into another vector in a column-major order . my problem is that the vector returns the location of the last element, it overrides the elements before it instead of concatenating it. e,g if the locations of the elements are (1,2) (3,2) (4,1). it returns only (4,1). how do I make it to concatenate and how do I set it to column-major order?

[Azzi Abdelmalek]

Your question is not clear, post your code, you can also, illustrate with an example

Answer 1

[OLUBUKOLA ogunsola]

indexes=[]; for ii= 1:size (X,1); for jj = 1: size (X , 2); if X(ii , jj)< ii*jj; indexes = {ii ,jj}; end end end

Answer 2

[Jos (10584)]

X = randi(20,6,4)

[ii,jj] = ndgrid(1:size(X,1), 1:size(X,2)) 
tf = X < ii.*jj
ii(tf) 
jj(tf)

[OLUBUKOLA ogunsola]

sorry i don't really understand what is going on here ,but the code failed for X = [0;1;2;3;4;5;6;7;8;9;10]. this is what i got

ans =

     1
     2
     3
     4
     5
     6
     7
     8
     9
    10
    11

ans =

     1
     1
     1
     1
     1
     1
     1
     1
     1
     1
     1

[Jos (10584)]

What did you expect? This code produces the rows ii and columns jj were X(ii,jj) < ii*jj ...

[OLUBUKOLA ogunsola]

this is what i came up with with your suggestions : function indexes = small_elements ( X) indexes=[]; for ii= 1:size (X,1); for jj = 1: size (X , 2); if X(ii , jj)< ii*jj; a=[ii jj]; indexes=[indexes; a]; end end end it passed for several inputs except [0;1;2;3;4;5;6;7;8;9;10] I'm sure sure it has to do with the column major order which is a condition required from the question of the output

[OLUBUKOLA ogunsola]

im pasting the code again because it was jumbled together

function indexes = small_elements ( X)

indexes=[];

for ii= 1:size (X,1);

    for jj = 1: size (X , 2);

        if X(ii , jj)< ii*jj;

            a=[ii jj];

            indexes=[indexes; a];

        end 
    end 
end

[Jos (10584)]

Without an input, how can we know your code is incorrect?