If I get your problem right, you could use "combnk"
If V is a vector with the indices of your N's, e.g.
V = 1:10
then
combnk(V,3)
gives a matrix whose rows are the combinations of 3 indices taken out of V. So, your code might be something like this
L = 10; % number of N
V = 1:L;
for n = 1:L
C = combnk(V,n); % this is a matrix
% loop over its rows
for r = 1:size(C,1)
c = C(r,:); % this is one particular combination of n elements
% <<< here you do whatever calculation you need to do based on c
end
end
By the way, since each N has 5 entries, it could be worth forming a Lx5 matrix Nm out of it. This way
Nm(c,:)
should contain only the values you need for your calculation with the particular combination in c.
