Various methods of calculating Fibonacci numbers in PHP

gistfile1.php

<?php

/**
 * Various methods of computing Fibonacci numbers in PHP
 */
class Fibonacci
{
    /**
     * @var array Memoization cache
     * @see Fibonacci::memoized
     */
    protected $cache = array(0 => 0, 1 => 1);
    
    /**
     * Fibonacci using recursion
     */
    public function recursive($n)
    {
        if ($n == 0) {
            return 0;
        }

        if ($n == 1) {
            return 1;
        }

        return $this->recursive($n - 1) + $this->recursive($n - 2);
    }
    
    /**
     * Fibonacci using an iterative approach
     */
    public function iterative($n)
    {
        $a = 0;
        $b = 1;

        for ($i = 0; $i < $n; $i++) {
            $c = $a;
            $a = $b;
            $b += $c;
        }

        return $a;
    }
    
    /**
     * Fibonacci using Binet's formula
     * @link http://mathworld.wolfram.com/BinetsFibonacciNumberFormula.html
     */
    public function binet($n)
    {
        $phi = (1 + sqrt(5)) / 2;

        return (pow($phi, $n) - pow(1 - $phi, $n)) / sqrt(5);
    }

    /**
     * Fibonacci using a cache
     */
    public function memoized($n)
    {
        if (!isset($this->cache[$n])) {
            $this->cache[$n] = $this->memoized($n - 1) + $this->memoized($n - 2);
        }

        return $this->cache[$n];
    }
}

/**
 * Test each Fibonacci method and output the speed
 */
function test($total, $callback)
{
    echo $callback[1] . ":\n";
    $t = microtime(true);
    for ($x = 0; $x < $total; $x++) {
        call_user_func($callback, $x);
    }
    $finish = microtime(true) - $t;
    echo ($finish * 1000) . ' ms (' . (($finish / $total) * 1000) . ")\n\n";
}

// You can pass in the total number of sequences to calculate as a CLI argument
$total = isset($argv[1]) ? $argv[1] : 25;

$fib = new Fibonacci();
test($total, array($fib, 'iterative'));
test($total, array($fib, 'binet'));
test($total, array($fib, 'memoized'));

// Limit our attempts with recursion
if ($total <= 30) {
    test($total, array($fib, 'recursive'));
}

Thank you, this was super useful. Here's the results for anyone interested: https://3v4l.org/5ksoN

You really explained very well. All the algorithms and formulas are included to calculate the Fibonacci Series. Helped a lot.