Find vector elements that sum up to specific number in MATLAB

Question

Let us consider that we have a vector VEC.

Is ther a way to find which vector elements can be grouped so as they sum up to a given number NUM in MATLAB?

Answer 1

Here's another way to do it without any toolboxes or third party functions. It steps through all possible combinations of values in VEC and tests if the sum equals NUM.

VEC = [2 5 7 10]
NUM = 17;
n = length(VEC);
for i = 1:(2^n - 1)
    ndx = dec2bin(i,n) == '1';
    if sum(VEC(ndx)) == NUM
        VEC(ndx)
    end
end

ans =
     7    10
ans =
     2     5    10

This is similar to natan's answer, but without using conbntns.