Help with function that uses a while statement to get the next largest prime number

Hi, I am working on an assignment that requires finding the next largest prime number k after the input n. I feel like I am not succesfully using the while loop statement and I was wondering if anyone had suggestions as my output is just n+1. I know I am structuring this in a way that my i being used in my last if statement (i=k) is not coming from the while loop and thats about as far as I can get.

function k = next_prime1(n)
if n<1||~isscalar(n)||n==~fix(n)
    error('integer not a whole positive number')
else
    i=n+1;
    while ~isscalar(i)
        i=i+1;
    end
    if isscalar(i)
        k=i
    end
end

[Sana Hafeez]

I can't solved my assignment by using that code please help

[Walter Roberson]

Well, see the discussion below as to what the bug was in the code that was posted.

Answer 1

[Walter Roberson]

isscalar() is a test to see if size() of the argument is all 1's -- not empty, not 2D, just a single element.

isscalar() has nothing to do with whether a value is prime.

isscalar(n) is a good test for valid inputs. But you should do it first

if ~isnumeric(n) || ~isscalar(n) || n < 1 || n==~fix(n)

otherwise if the user passes in something non-scalar you would be testing that non-scalar value against 1, which would give a non-scalar result and then the || would fail. Postpone all your numeric tests until you know that the input is a numeric scalar.

But after that... you should be testing for prime, not testing for scalar.

[Jessamyn Johnson]

ahhh thank you I can't believe I put in isscalar istead of isprime!!! haha I feel so stupid, the function works now that I have actually put in isprime. oh my gosh how did I miss that