# Counting consecutive negative numbers in an array

2 views (last 30 days)
BN on 24 Nov 2020
Commented: BN on 24 Nov 2020
Hello, I need to find how many times consecutive negative numbers are in the array. For example:
v = [11 2 3 -1 -2 1 -1 -1 -3 1 3 -1];
The answer must be: 3
Thank you
##### 0 CommentsShow -2 older commentsHide -2 older comments

Sign in to comment.

### Accepted Answer

Bruno Luong on 24 Nov 2020
Edited: Bruno Luong on 24 Nov 2020
length(strfind([false v<0],[0 1]))
or
sum(diff([false v<0])==1)
##### 3 CommentsShow 1 older commentHide 1 older comment
Bruno Luong on 24 Nov 2020
Edited: Bruno Luong on 24 Nov 2020
How do you get 2?
>> v= [11 2 3 -1 -2 1 -1 -1 -3 1 3 -1]
v =
11 2 3 -1 -2 1 -1 -1 -3 1 3 -1
>> length(strfind([false v<0],[0 1]))
ans =
3
>> sum(diff([false v<0])==1)
ans =
3
BN on 24 Nov 2020
Thank you so much. I forgot to use the clear command then try the code. After that, your code works very well.
Thank you it is really helpful for me

Sign in to comment.

### Categories

Find more on Multidimensional Arrays in Help Center and File Exchange

R2020a

### Community Treasure Hunt

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

Start Hunting!