static function prepareWords($words) {
$words=SearchEngine::normalizeWords($words);
$words = explode(" ",$words);
$i=0;
while ($i<sizeof($words)){
$words[$i]=trim($words[$i]);
if (strpos(SearchEngine::$stopwords,",".$words[$i].",")!==false) {$words[$i]='';}
else $words[$i] = SearchEngine::getRadical($words[$i]);
if (strpos(SearchEngine::$stopwords,",".$words[$i].",")!==false) {$words[$i]='';}
$words[$i]=trim($words[$i]);
$i++;
}
return $words;
}