title: Why does this PHP function return the wrong result?
body: <p>I wrote a user function to return the distance between two points on an x,y coordinate system.  The input params were <code>0,0,10,10</code>.</p>
  
  <p>Here is the original code:</p>
  
  <pre><code>public static function dist2d($x1,$y1,$x2,$y2) {
     return sqrt((($x2 - $x1) * ($x2 - $x1)) + (($y2 - $y1) * ($y2 - $y1)));
  }
  </code></pre>
  
  <p>This returns 110.</p>
  
  <p>Here is the code that works:</p>
  
  <pre><code>public static function dist2d($x1,$y1,$x2,$y2) {
      $result = (($x2 - $x1) * ($x2 - $x1)) + (($y2 - $y1) * ($y2 - $y1));
      return sqrt($result);
  }
  </code></pre>
  
  <p>This returns <code>14.1</code>.</p>
  
  <p>I am new to PHP, what is going on here?</p>