recognition of different cases

In an assignment for class, one of the problems asks for a function that recognizes any variation of "yes" or "no," such as yES, YEs, No, nO. The question suggests we use the "upper" command. Here's what I have so far, but I feel like I'm approaching it incorrectly

    % code
  end
yesorno = input('Run the function again? (Yes/No)\n');
yes = 1;
no = 2;
if yesorno == 1
    disp('Function restart...')
else 
end

Answer 1

[Azzi Abdelmalek]

yesorno = input('Run the function again? (Yes/No)\n','s')

Then compare upper(yesorno) with 'YES' or 'NO'