Vectorization of a for loop (addition of a vector)

Hello MATLAB community,

I have a question concerning the vectorization of a for loop to speed up my code. What I have is a vector, let´s say:

a = [1 2 3 4 5 6 7 8 ]

What I want to do is to create a vector, which makes an addition of all values in the vector to the point which I am actually at. In this case it would be:

a_new = [1 3 6 10 15 21 28 36]

It´s no problem to code this with a for loop.

s_neu = zeros (1,length(s),'double');

s_neu(1,1) = s(1,1);

for i = 2:length(s)

      s_neu(1,i) = s_neu(1,i-1)+s(1,i);

end

Do anyone of you know, how to code this without the for loop? Thank you very much!

Answer 1

[Mohammad Abouali]

This is cumulative sum so use cumsum function

a = [1 2 3 4 5 6 7 8 ] 
a_new=cumsum(a)
a_new =
     1     3     6    10    15    21    28    36