matlab - How to generate a matrix of vector combinations with zeros for excluded elements? -

i want create matrix combinations of elements of 1 vector fulfill condition

for example, have vector

a = [1 2 3 4 5] 

and want create matrix

a = [1 0 0 0 0;      1 2 0 0 0;      1 2 3 0 0;      1 2 3 4 0;      1 2 3 4 5;      0 2 0 0 0;      0 2 3 0 0;      ........;] 

and rows fulfill condition can use command:

b = sum(a')' > value 

but don't know how generate matrix

you can generate possible binary combinations determine matrix want:

a = [1 2 3]; n = size(a,2);  % generate bit combinations c =(dec2bin(0:(2^n)-1)=='1'); % remove first line c = c(2:end,:) n_c = size(c,1);  a_rep = repmat(a,n_c,1); result = c .* a_rep 

output:

c =   0     0     1  0     1     0  0     1     1  1     0     0  1     0     1  1     1     0  1     1     1   result =   0     0     3  0     2     0  0     2     3  1     0     0  1     0     3  1     2     0  1     2     3