# Stop a sum of numbers until a certain value is reached

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Pilar Jiménez on 21 Oct 2019
Commented: Pilar Jiménez on 22 Oct 2019
If I have defined values
Nmax = 15;
A = [2 5 4 6 1];
I want to make a sum of each value of A in the order in which it is found until it reaches Nmax, if the value is equal to or greater than Nmax the sum stops and the number or numbers that have been pending to be added are saved in another vector B.
How did you get the sum to stop and tell me the index of the vector at which it stopped to be able to save the values forward in the other vector?

Image Analyst on 21 Oct 2019
You can use cumsum() to do it vectorized, like most MATLABers would:
Nmax = 15;
A = [2 5 4 6 1];
ca = cumsum(A) % Sum them all up
lastIndex = find(ca <= Nmax, 1, 'last') % Last index before the sum would exceed Nmax.
% Show what elements they were "Pending" (whatever that means in this context).
B = A(lastIndex + 1 : end) % The remaining numbers
Pilar Jiménez on 22 Oct 2019
Thank you for your help. It really helps me a lot for what I have to do, I've been trying for a long time, I didn't know that the "cumsum" command existed.