Do a cross-set operation on a matrix

I have a matrix which looks as follows:

[1 2 3;
 4 5 6]

I want to do a cross-set operation on itself, so that each element is associated with every other element, like this:

[1 2 3;
 4 2 3;
 1 5 3;
 4 5 3;
 1 2 6;
 4 2 6;
 1 5 6;
 4 5 6]

Can someone please help me/point me in right direction?

Answer 1

[Sean de Wolski]

A = [1 2 3; 4 5 6]; %data
[xx yy zz] = meshgrid(1:2,3:4,5:6); %column-wise linear indices
B = [A(xx(:)) A(yy(:)) A(zz(:))] %extract

More - generalized to n-dimensions and rows:

A = [1 2 3 7; 4 5 6 9]; %data
[nr nc] = size(A);
C = num2cell(reshape(1:(nr*nc),nr,nc),1);
X = cell(nc,1);
[X{1:nc}] = ndgrid(C{:}); %column-wise linear indices

for ii = nc:-1:1
  V(:,ii) = A(reshape(X{ii},[],1));
end

[Vinay Pandey]

Can this be extended to matrix with 'n' number of columns?

[Sean de Wolski]

sure.

[Vinay Pandey]

What I mean to ask was, how can we extend it to n-columns, when we don't know the number of columns in advance.

[Sean de Wolski]

see edit

[Vinay Pandey]

Thanks!