You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: tldNN.m
    path of file: ./repos/OpenTLD/tld
    
    the code of the file until where you have to start completion: % Copyright 2011 Zdenek Kalal
%
% This file
    
function [conf1,conf2,isin] = tldNN(x,tld)
% 'conf1' ... full model (Relative Similarity)
% 'conf2' ... validated part of model (Conservative Similarity)
% 'isnin' ... inside positive ball, id positive ball, inside negative ball

isin = nan(3,size(x,2));

if isempty(tld.pex) % IF positive examples in the model are not defined THEN everything is negative
    conf1 = zeros(1,size(x,2));
    conf2 = zeros(1,size(x,2));
    return;
end