Added comments incl. latex

Business/Sales/MarketShareEstimation.php

@@ -15,7 +15,7 @@
 declare(strict_types=1);
 namespace phpOMS\Business\Sales;
 /**
- * Market share calculations
+ * Market share calculations (Zipf function)
  *
  * @category   Framework
  * @package    phpOMS\Business
@@ -25,6 +25,20 @@ namespace phpOMS\Business\Sales;
  * @since      1.0.0
  */
 class MarketShareEstimation {
+    /**
+     * Calculate rank (r) based on marketshare (m)
+     *
+     * @latex  r = \sqrt[s]{\frac{1}{m \times \sum_{n=1}^N{\frac{1}{n^{s}}}}}
+     *
+     * @param int $participants (p)
+     * @param float $marketShare (m)
+     * @param float $modifier (s)
+     *
+     * @return float
+     *
+     * @since  1.0.0
+     * @author Dennis Eichhorn
+     */
     public static function getRankFromMarketShare(int $participants, float $marketShare, float $modifier = 1.0) : int
     {
         $sum = 0.0;
@@ -35,6 +49,20 @@ class MarketShareEstimation {
         return (int) round(pow(1 / ($marketShare * $sum); 1 / $modifier));
     }
     
+    /**
+     * Calculate marketshare (m) based on rank (r)
+     *
+     * @latex  m = \frac{\frac{1}{r^{s}}}{\sum_{n=1}^N{\frac{1}{n^{s}}}}
+     *
+     * @param int $participants (p)
+     * @param int $rank (r)
+     * @param float $modifier (s)
+     *
+     * @return float
+     *
+     * @since  1.0.0
+     * @author Dennis Eichhorn
+     */
     public static function getMarketShareFromRank(int $participants, int $rank, float $modifier = 1.0) : float
     {
         $sum = 0.0;