d-column combinations of matrix A n by n

Hi I'm trying to write an m file which takes a binary sparse matrix A and tests whether this matrix is a d-disjunct matrix.

( definition of D-disjunct : An n × t matrix M over {0, 1} is d-disjunct if d < t and for any one column j and any other d columns j1, j2, . . . , jd, there exists a row i such that Mij =1 and Mijs=0 for s=1,2,...,d.)

(i.e Pick a subset S ( not necessarily together). Then pick a column that is not present in that subset. There will always be i such that 1 in column j and all zero in subset exists.)

To be able to test, I need all d-column combinations and compare them to other columns(which are not part of the combination set).

I started to do this way but I do not know is there a short way to do it.

Matlab code 
combinations=nchoosek(length(A(1,:)), d)
for i=1:length(combinations(:,1))
   dcombin = A(:,combinations(1,:));
   %dunion = find union of all columns in dcombin
   %compare it to all other columns
   %

My question : How I can get d-column combinations and find its union.

Thank you in advance in case of one answers this question.

Answer 1

[Bruno Luong]

Another way is:

any(A,2)

[Jan]

+1. If I compare the number of characters in the question and in this answer, I register a certain discrepancy.

Answer 2

[Bruno Luong]

I'm not ths is what you want:

A=rand(10,5)>0.9

% Union of all columns of A
logical(sum(A,2))

[Mehmet Candemir]

thanks. That's the one I found after a while. Though, the second way is better and more elegant.