Step one: check the given number is fibonacci or not.

answer3.php

$input = array(1,22,9,0);
var_dump(nextFibonacci($input)); //output [2,34,13]

function nextFibonacci($input) {
    foreach($input as $i) {
        while($i>=0) {
            $store[] = $i;
            if(isFibonacci($i)) 
            break;
            $i--;
        }
        $last = end($store);
        if($last == 0) {
            $output[] = 1;
        } else {
            $output[] = round($last/0.618);
        }
    }
    return $output;
}

//Checking for square root
function isPerfectSquare($x) 
{ 
    $s = (int)(sqrt($x)); 
    return ($s * $s == $x); 
}

// n is Fibinacci if one of  
// 5*n*n + 4 or 5*n*n - 4 or  
// both is a perferct square 
function isFibonacci($n) 
{ 
  return isPerfectSquare(5 * $n * $n + 4) || isPerfectSquare(5 * $n * $n - 4); 
}