summing up array element
3 visualizzazioni (ultimi 30 giorni)
Mostra commenti meno recenti
Hello,
I am new to programming, I have an array like p = [3 6 2 5];
I need c = [3 9 11 16]; First element in the array is as it is, when it goes to next element it has to sum the previous element.
Regards, SBN
Risposte (4)
Andrew Reibold
il 25 Lug 2013
Modificato: Andrew Reibold
il 25 Lug 2013
Here is your solution in a really easy loop.
p = [3 6 2 5]; %Can have as many numbers as you want
for n = 2:length(p) %n can be whatever counter you want.
p(n) = p(n)+p(n-1); %semi-colon suppresses output
end
-Andrew
Iain
il 25 Lug 2013
Modificato: Iain
il 25 Lug 2013
for i = 1:numel(p)
c(i) = sum(p(1:i));
end
Or
so_far = 0;
for i = 1:numel(p)
so_far = so_far + p(i);
c(i) = so_far;
end
or
for i = 1:numel(p)
s = 0;
for j = 1:i
s = s+ p(j);
end
c(i) = s;
end
1 Commento
Jan
il 25 Lug 2013
These are inefficient solutions, because the complete sum is calculated in each iteration. While this might not matter for 4 elements, the runtime will grow rapidly for longer data.
It is more efficient to re-use the sum for the elements 1 to i, when the sum until the i+1.th element is obtained. See Andrews answer.
Vedere anche
Categorie
Scopri di più su Matrices and Arrays in Help Center e File Exchange
Community Treasure Hunt
Find the treasures in MATLAB Central and discover how the community can help you!
Start Hunting!