How to calculate a cumulative sum in a loop?

I have a loop that looks like this:

for a = 1: 9
    for b = 1 : 1000
        for c = 1 : 1000
            image = myimage_bands(b, c, a);
            new_image = image * 5;
        end   
    end
end

I am trying to find the cumulative sum of my variable 'new_image', as it goes through the loop. I've tried cumsum, but it doesn't work.

Any ideas are appreciated. Thanks!

[Azzi Abdelmalek]

There is no cumulative sum in your code, can you explain what you want?

Answer 1

[Walter Roberson]

Before the loop,

image_sum = [];

inside the loop after you have calculated new_image,

if isempty(image_sum)
  image_sum = new_image;
else
  image_sum(end+1) = image_sum(end) + new_image;
end

[Sandy]

Thank you! I have another question though. How would I change the code if my variable new_image was a matrix (6 x 6)?

[Walter Roberson]

image_sum(:,:,end+1) = image_sum(:,:,end) + new_image;