Re: Reducing for loop

[Przemek Klosowski]

On 03/25/2015 04:09 PM, Dr.-Ing. Dieter Jurzitza wrote:

Dear listmembers,
I am using a for loop as follows. I have an array, say A, containing numelem 
elements.

Now I want to fill array B with elements as follows:

B(1)=A(1)

for i=2:numelem
   B(i)=B(i-1)+A(i);
endfor

If you unroll that, I believe that you'd get:

    B(1) = A(1)
    B(2) = B(1) + A(2) = A(1) + A(2)
    B(3) = B(2) + A(3) = A(1) + A(2) + A(3)
    ...
    B(N) = ....              = A(1) + A(2) +...+A(N)

so, simply,

    B=cumsum(A)