Hello IDN,
I can understand that you want to calculate prefix sum of vector B based on condition provided by vector A. I have added a code sample for the same task below.
Assumption made
- Size of matrix A and B are equal
- Every -1 in matrix A is preceded by +1
A = [ 0 0 0 1 1 1 -1 0 0 1 1 -1]
B= [ 0 0 0 34 4 4 6 0 0 12 3 3]
sz =size(A)
% matrix to store the cummalative sum
cumSum = zeros(sz)
%flag variable to tell when to start add elements
startSum = true
for idx=1:sz(2)
if A(idx)==0
continue
elseif A(idx)==1
if startSum==true
cumSum(idx)=B(idx)
startSum=false
else
cumSum(idx)=B(idx)+cumSum(idx-1)
end
else
cumSum(idx)=B(idx)+cumSum(idx-1)
startSum=true
end
end
