do the elt is part of a fibonacci ?

gistfile1.php

function is_fibonacci_element($fib, $count, $limit = 100) {

	foreach($fib as $elt)
		if ( $count == $elt )
			return true;

	$idx = count($fib) - 1;
	while ($count > $fib[$idx] && $idx < 50) {
		$fib[] = $fib[$idx] + $fib[$idx - 1];
		$idx = count($fib) - 1;
		if ( $count == $fib[$idx] )
			return true;
	}

	return false;

}