Matlab - Suma de elementos de un vector por partes

>> clear all

A=[1 3 5 2 0 6 8 9 0 1 5 6];

i=1;

k=1;

while k<=length(A)/3

    s(k)=sum(A(i:i+2));

    i=i+3;

    k=k+1;

end

s

s =

       9              8             17             12

A=[1 3 5 2 0 6 8 9 0 1 5 6];

k=3; % toma de a k elementos

B=sum(reshape(A(1:(end-rem(numel(A),k))),k,floor(numel(A)/k)),1);

A=[0 0 2 4 0 0 0 5 8];

B=zeros(size(A));

k=1;

for j=1:numel(A)

    if A(j)==0

        k=k+1;

    end

    B(k)=B(k)+A(j);

end

B(B==0)=[];

disp(B)

T=[0.56 0.23 0.14 0.25 0.36 0.21 0.38 0. 78 ]

T =

    0.5600    0.2300    0.1400    0.2500    0.3600    0.2100    0.3800         0   78.0000

>> A=cumsum(T)

A =

    0.5600    0.7900    0.9300    1.1800    1.5400    1.7500    2.1300    2.1300   80.1300