# Cumulative sum between two trues in array according to positions stored in logical array

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Enrico Gambini on 17 Oct 2022
Edited: Matt J on 17 Oct 2022
Hello!
I would like to find a fast way to get cumulative sums of values of an array according to the starting and ending positions given by a logical array,
for instance:
v=[0;1;2;0;2;4;5;6;2;3;4];
pos=[true;false;true;false;false;true;false;true;false;false;true];
I would like the code to cumulative sum vector "x" between two trues, getting the following result:
result=[3;8;15;15]; %I summed [2+1+0;4+2+0+2;6+5+4;4+3+2+6]
Hope that the question is clear, thank you!

Matt J on 17 Oct 2022
Edited: Matt J on 17 Oct 2022
v=[0;1;2;0;2;4;5;6;2;3;4];
pos=[true;false;true;false;false;true;false;true;false;false;true];
cv=cumsum(v);
I=find(pos);
result = cv(I(2:end))-cv(I(1:end-1)) +v(I(1:end-1))
result = 4×1
3 8 15 15

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