using cumsum for a vector

I have a variable GT2, which is a 1x900 double.

I am trying to do a cumulative sum, where for each cell it does a cumulative sum up to that point, dives this by how many numbers has been summed, and then take the square root.

The current code I have for this is below. When I run this code, it creates a 900x900 double. All I want it to do is do that calculation for each cell so I end up with the same number of values (900) as in GT2. Can anybody help?

flucc = sqrt(cumsum(GT2)./time);

Answer 1

[Cris LaPierre]

Check your dimensaion. Your cumsum will be a 1xn vector. I suspect time must be an nx1. When you perform the division, implicit expansion will turn this into an nxn. The fix would be to transpose time.

% (1xn)./(1xn) = (1xn)
a = cumsum(1:4)./ones(1,4)

a = 1×4

1 3 6 10

% (1xn)./(nx1) = (nxn)
b = cumsum(1:4)./ones(4,1)

b = 4×4

1 3 6 10 1 3 6 10 1 3 6 10 1 3 6 10