# Store prime and non-prime numbers in two diferent vectors from a .txt

1 view (last 30 days)
ABG on 29 Sep 2022
Commented: ABG on 30 Sep 2022
Hi guys!
I am really new at programming with matlab, and I am stuck with one problem.
I need to read a bunch of numbers from a .txt file, determine whether this numbers are prime or not and finally store them in two diferent files.
With the code attached, what happens is that all the values from the .txt are stored in the nonprime_num vector, and I don't know why (I have tried many ways but none of them have worked).
If you could help me with this, I would be really grateful! Thank you very much!
x=Natural_numbers;
x=x'; % i want the data in a row
i=2;
prime=1;
n=length(x);
prime_num=[];
nonprime_num=[];
while i<=sqrt(x)
if rem(x,i)==0
prime=0;
break
end
i=i+1;
end
if prime==1
nonprime_num=[x, i];
else
prime_num=[x, i] ;
end

Eric Delgado on 29 Sep 2022
x = [1, 11, 21, 23, 25, 27, 29, 30, 31, 44];
idx = isprime(x);
Prime = x(idx)
Prime = 1×4
11 23 29 31
nonPrime = x(~idx)
nonPrime = 1×6
1 21 25 27 30 44
% writematrix(Prime, "Prime.txt")
% writematrix(nonPrime, "nonPrime.txt")
ABG on 30 Sep 2022
Thank you so much Eric!

David Hill on 29 Sep 2022
Edited: David Hill on 29 Sep 2022
Attach Natural_numbers.txt is below does not work
idx=isprime(m);
nonprime_num=m(~idx);
prime_num=m(idx);
ABG on 30 Sep 2022

### Categories

Find more on Loops and Conditional Statements in Help Center and File Exchange

R2019b

### Community Treasure Hunt

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

Start Hunting!