ho to find index at which the 50% of the sum vector is included?

3 views (last 30 days)
ho to find index at which the 50% of the sum vector is included?
a=[3 5 7 3 5 8 9 3 1 41 6];
sum(a)=91
50% of sum signal =45.5
indice which is approximately equal to of sum of 50% of sum signal a is 9

Answers (2)

Star Strider
Star Strider on 26 Nov 2021
A least-squared-difference approach works —
a=[3 5 7 3 5 8 9 3 1 41 6];
suma = cumsum(a);
suma50 = suma(end)/2;
[minv,idxv] = min((suma50-suma).^2)
minv = 2.2500
idxv = 9
.
  3 Comments
Star Strider
Star Strider on 26 Nov 2021
My pleasure!
If my Answer helped you solve your problem, please Accept it!
.
Steven Lord
Steven Lord on 26 Nov 2021
If you want the first index that's past the halfway point:
a=[3 5 7 3 5 8 9 3 1 41 6];
suma = cumsum(a)
suma = 1×11
3 8 15 18 23 31 40 43 44 85 91
suma50 = suma(end)/2
suma50 = 45.5000
[~, location] = find(suma > suma50, 1, 'first')
location = 10
suma([location-1 location])
ans = 1×2
44 85

Sign in to comment.


Image Analyst
Image Analyst on 27 Nov 2021
Isn't this a duplicate?
If it's not your homework, you can use my solution:
a = [3 5 7 3 5 8 9 3 1 41 6];
s = sum(a)
s = 91
c = cumsum(a)
c = 1×11
3 8 15 18 23 31 40 43 44 85 91
[minDiff, index] = min(abs(c - s/2))
minDiff = 1.5000
index = 9
(If it is your homework, tag it as homework and find a different way. Don't turn in any of our solutions as your own or you may get caught for cheating.)

Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!