fibonacci in php

<?php if(!empty($_GET[‘upto’])){ $upto = $_GET[‘upto’]; }else{ $upto = “”; } function getfibo($upto=5){ $second =1;¬† $first ¬†=0; $fibo_arr[] = $first; $fibo_arr[] = $second; for($i=1; $i<$upto; $i++){ $fibo_arr[]= ($fibo_arr[$i-1] + $fibo_arr[$i]); } $fseries = ¬†implode(‘,’,$fibo_arr); return $fseries; } echo getfibo($upto); ?>