remove count from test condition

composer.json

@@ -1,7 +1,7 @@
 {
     "name": "php-ai/php-ml",
     "type": "library",
-    "description": "PHP Machine learning library",
+    "description": "PHP Machine Learning library",
     "license": "MIT",
     "keywords": ["machine learning","pattern recognition","computational learning theory","artificial intelligence"],
     "homepage": "https://github.com/php-ai/php-ml",

src/Phpml/Metric/Distance.php

@@ -23,8 +23,9 @@ class Distance
         }
 
         $distance = 0;
+        $count = count($a);
 
-        for ($i = 0; $i < count($a); ++$i) {
+        for ($i = 0; $i < $count; ++$i) {
             $distance += pow($a[$i] - $b[$i], 2);
         }