function fib($n)
{
    if ($n < 2) {
        return 1;
    }
    return fib($n - 1) + fib($n - 2);
}

function fib($n)
{
    assert($n >= 0);
    if ($n === 0 || $n === 1) {
        return 1;
    }
    return fib($n - 1) + fib($n - 2);
}

function fib($i)
{
    if ($i < 2) {
        return $i;
    } else {
        return fib($i - 1) + fib($i - 2);
    }
}

function fib($n)
{
    if ($n > 1) {
        return fib($n - 2) + fib($n - 1);
    } else {
        return $n;
    }
}

function fib($num)
{
    if ($num < 2) {
        return $num;
    } else {
        return fib($num - 1) + fib($num - 2);
    }
}

function fib($n)
{
    if ($n < 2) {
        return 1;
    } else {
        return fib($n - 2) + fib($n - 1);
    }
}

function fib($one, $two)
{
    global $total;
    if ($one % 2 === 0) {
        $total += $one;
    }
    if ($two < 4000000) {
        fib($two, $one + $two);
    }
}

function tail_recurse($n)
{
    if ($n > 0) {
        tail_recurse($n - 1);
    }
    print $n;
    print ": ";
    print fib($n);
    print "\n";
}

function fib($n)
{
    if ($n == 0) {
        return 0;
    }
    if ($n == 1) {
        return 1;
    }
    return fib($n - 1) + fib($n - 2);
}

function fib($n = 1)
{
    if ($n == 0) {
        return 0;
    } elseif ($n == 1) {
        return 1;
    } else {
        return fib($n - 1) + fib($n - 2);
    }
}

function fib($num, $first_number = 5, $second_number = 5)
{
    $n = array(5, 5, 10, 15, 25, 40);
    $y = array($first_number);
    if ($num < 0) {
        return array($first_number);
    }
    echo "{$first_number}\n";
    $x = fib($num - 1, $second_number, $first_number + $second_number, $n);
    return array_merge($x, $y);
}

function fib($x, $y, $term)
{
    $fib = bcadd($x, $y);
    $term += 1;
    if (strlen($fib) >= 1000) {
        echo "Term is " . $term . "\n";
        result('4782', $term);
    } else {
        fib($y, $fib, $term);
    }
}

function main()
{
    $N = isset($_GET['N']) ? (int) $_GET['N'] : 24;
    if ($N < 2) {
        $N = 2;
    }
    if ($N > 500) {
        $N = 500;
    }
    $fibs = fib($N);
    render($fibs);
}

function fib($x, $y, $max, &$total)
{
    $fib = $x + $y;
    if ($fib <= $max) {
        if ($fib % 2 == 0) {
            $total += $fib;
        }
        $fib = fib($y, $fib, $max, $total);
        return $fib;
    } else {
        return 0;
    }
}

function fib($one, $two, $end)
{
    if ($end <= 0) {
        return;
    } else {
        echo "{$one} <br>";
        $end--;
        $one = $one + $two;
        $two = $one - $two;
        $one = $one - $two;
        fib($one, $two, $end);
    }
}

/**
 * @param int $x
 * @param array $series
 * @param int $n
 * @return array
 */
function fib_n_step($x, &$series = array(1, 1), $n = 15)
{
    $count = count($series);
    if ($count > $x && $count == $n) {
        return $series;
    }
    if ($count < $n) {
        if ($count >= $x) {
            fib($series, $x, $count);
            return fib_n_step($x, $series, $n);
        } else {
            while (count($series) < $x) {
                $count = count($series);
                fib($series, $count, $count);
            }
            return fib_n_step($x, $series, $n);
        }
    }
    return $series;
}

function fib($n)
{
    return $n > 0 ? fib($n - 1) + fib($n - 2) : 1;
}

<?php

function fib($n)
{
    if ($n < 0) {
        throw new Exception('Negative numbers not allowed');
    }
    $f = function ($n) {
        // This function must be called using call_user_func() only
        if ($n < 2) {
            return 1;
        } else {
            $g = debug_backtrace()[1]['args'][0];
            return call_user_func($g, $n - 1) + call_user_func($g, $n - 2);
        }
    };
    return call_user_func($f, $n);
}
echo fib(8), "\n";

<?php

function fib($n)
{
    if ($n <= 1) {
        echo $n;
    }
    $aux1 = 0;
    $aux2 = 1;
    for ($i = 2; $i <= $n; $i++) {
        $cont = $aux1;
        $aux1 = $aux2;
        $aux2 = $cont + $aux1;
    }
    echo $aux2;
}
//Como ainda não aprendi a pegar um número via teclado!
//Teste essa função passando o número dentro da função  fib(numero aqui);
fib(10);

 */
/*Zadanie *. Napisz funkcję, która oblicza kolejne wyrazy ciągu Fibonacciego
(http://pl.wikipedia.org/wiki/Ci%C4%85g_Fibonacciego) aż do podanej zmiennej. Nie używaj do tego rekurencji.*/
function fib($x)
{
    $pierwszy = 1;
    $drugi = 1;
    if ($x == 1) {
        return 1;
    } elseif ($x == 2) {
        return 1;
    } else {
        $licznik = 3;
        while ($licznik <= $x) {
            $rezultat = $pierwszy + $drugi;
            $pierwszy = $drugi;
            $drugi = $rezultat;
            $licznik = $licznik + 1;
        }
        return $rezultat;
    }
}
$i = 19;
echo $i . ' elementem ciagu Fibonacciego obliczonego nierekurencyjnie jest ' . fib($i);
?>