cumulative geometric average returns

I have a range of returns for a certain number of days. I'm wondering how I could calculate the cumulative geometric average returns.

Eg. day 1 return =5 % day 2 return =-1% day 3 return =4

so the cumulative geometric average return for day one would be (1+0.05)^(1/1)-1

For day 2 it would be ((1+0.05)*(1+0.99))^(1/2)-1

and for day 3 it would be ((1+0.05)*(1+0.99)*(1+0.04))^(1/3)-1

Rg=((1+R1)*(1+R2)*(1+R3)...(1+Rn))^(1/n)-1

I am unsure about the logic needed for the accumulation because I am multiplying the returns together rather than adding

where I could do something like sum=sum+return to find an average for example.

Answer 1

[KSSV]

Let R be your array of size 1*n.

iwant = cumprod(1+R).^(1./(1:n))-1

[Asanka Subasinghe]

I know this is MATLAB Answers, but I am doing this with VBA. So I can only access a cell at a time using a for loop,

and I am trying to do it without using an inbuilt function.

[KSSV]

R = 1:5 ; 
n = 5 ; 
iwant = cumprod(1+R).^(1./(1:n))-1 ;   % Using inbuilt functions 
% Using loops 
CR = zeros(1,n) ; 
for i = 1:n
  T = 1 ; 
  for j = 1:i
    T = T*(1+R(j)) ; 
  end
  CR(i) = T^(1/i)-1 ; 
end
isequal(iwant,CR)

[Asanka Subasinghe]

Thank you!

[KSSV]

Thanks ia accepting the answer.