Cannot find where I am hitting recursion limit

Hi, matlab continues to tell me that I am getting a recursion limit problem with this code and I can't seem to see where my code is over doing itself. If you could help, that would be great. For me, I used k = 19 and received the problem. Please note that the function phi(k) is not where the issue is coming from

function PR(k)
    function out = phi(k)
        out = phi(k);
    end
if k > 1 && rem(k,1)==0
for i = 1:k
    if rem(k,i)==0
        y(i) = k./i;
    else
        y(i) = 1;
    end
end
for m = 1:k
    z(m) = mod(y(m).^y(m),k);
    if mod(z(m)-1,phi(k))==0
        w(m) = z(m);
    else
        w(m) = 1;
    end
end
else
    disp('Please make sure your input is an integer greater than 1');
end
end

Answer 1

[Sean de Wolski]

The issue is indeed from calling phi(k)

   function out = phi(k)
        out = phi(k);
    end

Calls itself infinitely and causes the recursion error.

%

[Tony]

Since the function ends though, why does it keep calling itself? Like, shouldn't the code begin, enter the function that calls phi, generate an output, end, then continue with rest of code?

[Sean de Wolski]

It never gets to the end. It calls phi, i.e. itself, again and then jumps back into itself on the next iteration once again calling itself before reaching the end.

What do you actually want phi to do?