MATLAB Answers

# While loop for testing the end of vector (Matlab)

1 view (last 30 days)
Afluo Raoual on 17 Feb 2021
Commented: Afluo Raoual on 17 Feb 2021
Dear members,
If we have a long vector that we don't know its length, and we want use while loop to repeat the task than stop and exit from the loop when the vector length is at its end.
For example, if the vector length is 10000 bits so we repeat the calculation (of any task) until 10000 than we stop and exit.
But in my case, I don't know the length of my vector. So how can I program this please?
Thank you.
##### 0 CommentsShowHide -1 older comments

Sign in to comment.

### Accepted Answer

Rik on 17 Feb 2021
You can use numel to create a loop over a vector of unknown size:
A=rand(1,100);
for n=1:numel(A) % n will go to 100
%your code here
end
##### 5 CommentsShowHide 4 older comments
Afluo Raoual on 17 Feb 2021
It's done

Sign in to comment.

### More Answers (1)

Daniel Pollard on 17 Feb 2021
Edited: Daniel Pollard on 17 Feb 2021
If you know that it's 1-dimensional, you can use
numel(vector)
which returns the length of your vector. Also useful to know is
size
which returns the size of a matrix (eg, [2 2] for a 2x2 matrix, [10 1] for a 10x1 vector, etc).
Edit I've replaced length with numel - thank you Rik.
##### 3 CommentsShowHide 2 older comments
Rik on 17 Feb 2021
The bug is not with length, the bug is with the use of length. For a vector it is equivalent to numel, and for array inputs it is probably not what you mean. How often did you want to loop over max(size(A)) without knowing which dimension is that maximum?

Sign in to comment.

### Community Treasure Hunt

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

Start Hunting!