Approximate PI using Monte Carlo method

pi_approximation.php

<?php

declare(strict_types=1);

include 'vendor/autoload.php';

use loophp\collection\Collection;

$monteCarloMethod = static function ($in = 0, $total = 1) {
    $randomNumber1 = mt_rand() / mt_getrandmax();
    $randomNumber2 = mt_rand() / mt_getrandmax();

    if (1 >= (($randomNumber1 ** 2) + ($randomNumber2 ** 2))) {
        ++$in;
    }

    return [$in, ++$total];
};

$precision = new class() {

    /**
     * @var array
     */
    private $state;

    /**
     * @var float
     */
    private $precision;

    /**
     * @var int
     */
    private $row;

    /**
     * Precision constructor.
     *
     * @param float $precision
     * @param int $row
     */
    public function __construct(float $precision = 10 ** -4, int $row = 100)
    {
        $this->precision = $precision;
        $this->row = $row;
        $this->state = [
            'prev' => null,
            'found' => 0,
        ];
    }

    /**
     * @param float $value
     *
     * @return bool
     */
    public function __invoke(float $value): bool
    {
        if (null === $this->state['prev']) {
            $this->state['prev'] = $value;
            $this->state['found'] = 0;

            return false;
        }

        if ($value === $this->state['prev']) {
            $this->state['found'] = 0;

            return false;
        }

        if (abs($value - $this->state['prev']) <= $this->precision) {
            ++$this->state['found'];

            return false;
        }

        if ($this->state['found'] >= $this->row) {
            $this->state['found'] = 0;

            return true;
        }

        $this->state['prev'] = $value;
        $this->state['found'] = 0;

        return false;
    }
};

$pi_approximation = Collection::iterate($monteCarloMethod)
    ->map(
        static function ($value) {
            return 4 * $value[0] / $value[1];
        }
    )
    ->nth(50) // Take every 50
    ->until($precision)
    ->last();

print_r($pi_approximation);