How do I avoid using for loop and vectorize when the i+1 th element of the array depends on the ith

I want to do the following without the for loop

x=zeros(size(RB_all_m,1),1);
y=zeros(size(RB_all_m,1),1);
index_1=zeros(size(RB_all_m,1),1);

x=sum(indices(1:690,:).*RB_all_m(2:691,:),2);
y=sum(indices(1:691,:).*RB_all_m(1:691,:),2);

for i=1:(size(RB_all_m,1)-1),
    index_1(i+1) = index_1(i)*x(i)./y(i);
end

Answer 1

[Andrei Bobrov]

index_1 = cumprod(x./y)

[Chetak]

This does the trick.

Thanks Andrei.