How to calculate price weighted function?

I'm trying to calculate the following function in Matlab. This is what I have tried so far but it gives me NaN. Can someone help?

Answer 1

[Mahmoud Ashraf]

avg=rand(1,505);
sum=0;
for j=1:505
sum=sum+avg(1,j);
end
for m=1:505
    pweight(1,m)=avg(1,j)/sum;
end

[de Bord Julien]

I'm still having trouble when I try to plug in the price data instead of rand(1,505):

I still keep getting NaN. Do you know why?