Added intergration of Monte Carlo for PHP (#431)

Author: PudottaPommin

contents/monte_carlo_integration/code/php/monte_carlo.php

@@ -0,0 +1,33 @@
+<?php
+declare(strict_types=1);
+
+function in_circle(float $positionX, float $positionY, float $radius = 1): bool
+{
+    return pow($positionX, 2) + pow($positionY, 2) < pow($radius, 2);
+}
+
+function random_zero_to_one(): float
+{
+    return mt_rand() / mt_getrandmax();
+}
+
+function monte_carlo(int $samples, float $radius = 1): float
+{
+    $inCircleCount = 0;
+
+    for ($i = 0; $i < $samples; $i++) {
+        if (in_circle(random_zero_to_one() * $radius, random_zero_to_one() * $radius, $radius)) {
+            $inCircleCount++;
+        }
+    }
+
+    return 4 * $inCircleCount / $samples;
+}
+
+$piEstimate = monte_carlo(10000000);
+$percentError = abs($piEstimate - pi()) / pi() * 100;
+
+printf('The estimate of PI is: %s', $piEstimate);
+echo PHP_EOL;
+printf('The percent error is: %s', $percentError);
+echo PHP_EOL;

contents/monte_carlo_integration/monte_carlo_integration.md

@@ -71,6 +71,8 @@ each point is tested to see whether it's in the circle or not:
 [import:1-4, lang:"ruby"](code/ruby/monte_carlo.rb)
 {% sample lang="f90" %}
 [import:1-8, lang:"fortran"](code/fortran/monte_carlo.f90)
+{% sample lang="php" %}
+[import:4-7, lang:"php"](code/php/monte_carlo.php)
 {% sample lang="lua" %}
 [import:1-3, lang="lua"](code/lua/monte_carlo.lua)
 {% sample lang="racket" %}
@@ -147,6 +149,8 @@ Feel free to submit your version via pull request, and thanks for reading!
 [import, lang:"ruby"](code/ruby/monte_carlo.rb)
 {% sample lang="f90" %}
 [import, lang:"fortran"](code/fortran/monte_carlo.f90)
+{% sample lang="php" %}
+[import, lang:"php"](code/php/monte_carlo.php)
 {% sample lang="lua" %}
 [import, lang="lua"](code/lua/monte_carlo.lua)
 {% sample lang="racket" %}