is always false with i not defined as a variable, because it tests the type of the imaginary unit. So getting past line 3 is not the issue, although Duane certainly points to an error in the code.
How do you get past line 3?:
clear all
j=input('Enter the value of "N": ');
if ischar(i)==1%Exception handling for char input
fprintf('Please enter an integer value')
break;
end
