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

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!

load('Natural_numbers.txt'); %loading the data
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

Answer 1

[Eric Delgado]

% x = load('Natural_numbers.txt');
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]

Thank you so much Eric!

Answer 2

[David Hill]

Attach Natural_numbers.txt is below does not work

m=readmatrix('Natural_numbers.txt');
idx=isprime(m);
nonprime_num=m(~idx);
prime_num=m(idx);

[ABG]

Thanks David for your answer. So much help!