Matlab confirm is input is not an array

Confirm that the input is a positive integer and not an array. I got this far, but when I type in [1 2 3] is does not prompt to enter in the positive integer again.

n = input('Enter in a positive integer: ')
while (n<0) & (isvector(n))
    n = input('Enter in a positive integer: ')
end

Answer 1

[Azzi Abdelmalek]

n = input('Enter in a positive integer: ')
while n<0 | numel(n)>1 | fix(n)~=n
  n = input('Enter in a positive integer: ')
end

[Walter Roberson]

Test the number of elements first. "n<0" is false if you have a vector that contains a mix of negative and non-negative values.