MATLAB: I need some help on matrix operations!

Question

if i have the index matrix a

a=[0 1 0 1 1 0 1]

and matrix b contains the actual values

v=[2 3 4 2 6 1 8]

here i'm going to check if a(i)=1 then i'm going to do the following:

a(2)=1 then sum=v(4)+v(5)+v(7)

and this will be done again to each one alone..

how to do that in an optimal way?

Answer 1

do you need something like this:

a=[0 1 0 1 1 0 1];
v=[2 3 4 2 6 1 8];
for i = 1:numel(a)
    sum = 0;
    for j = i:numel(a)
        if a(j) == 1
            sum = sum + v(j);
        end
    end
    sumArray(i) = sum;
end