Daniel@0: function sub_s=subsets1(s,k)
Daniel@0: % SUBSETS1 creates sub-sets of a specific size from a given set
Daniel@0: % SS = subsets1(S, k)
Daniel@0: % 
Daniel@0: % S is the given set
Daniel@0: % k is the required sub-sets size
Daniel@0: % 
Daniel@0: % Example:
Daniel@0: % 
Daniel@0: % >> ss=subsets1([1:4],3);
Daniel@0: % >> ss{:}
Daniel@0: % ans =
Daniel@0: %      1     2     3
Daniel@0: % ans =
Daniel@0: %      1     2     4
Daniel@0: % ans =
Daniel@0: %      1     3     4
Daniel@0: % ans =
Daniel@0: %      2     3     4
Daniel@0: % 
Daniel@0: % Written by Raanan Yehezkel, 2004
Daniel@0: 
Daniel@0: if k<0 % special case
Daniel@0:     error('subset size must be positive');
Daniel@0: elseif k==0 % special case
Daniel@0:     sub_s={[]};
Daniel@0: else
Daniel@0:     l=length(s);
Daniel@0:     ss={};
Daniel@0:     if l>=k
Daniel@0:         if k==1 % Exit condition
Daniel@0:             for I=1:l
Daniel@0:                 ss{I}=s(I);
Daniel@0:             end
Daniel@0:         else
Daniel@0:             for I=1:l
Daniel@0:                 ss1=subsets1(s([(I+1):l]),k-1);
Daniel@0:                 for J=1:length(ss1)
Daniel@0:                     ss{end+1}=[s(I),ss1{J}];
Daniel@0:                 end
Daniel@0:             end
Daniel@0:         end
Daniel@0:     end
Daniel@0:     sub_s=ss;
Daniel@0: end