Haar Feature-based Cascade Classifier XML File Argument

I am working on facial recognition based on harachnic cascade classifier. I have searched a lot but I still haven't found the exact answer for left_val and right_val in the XML file (like this)

  <_>
        <!-- root node -->
        <feature>
            <rects>
                <_>3 7 14 4 -1.</_>
                <_>3 9 14 2 2.</_></rects>
            <tilted>0</tilted></feature>
        <threshold> 4.0141958743333817e-003 </threshold>
        <left_val> 0.0337941907346249 </left_val>
        <right_val> 0.8378106951713562 </right_val></_></_>
  <_>

      

        
        
        
      

    

Left_val and right_val are the return value of the function (alpha (i) * h (i) in Viola-jones paper) that's true. And if so, because h (i) is -1 or 1, so we should have left_val = - right_val, but in the face it is not correct. Can you guys give me some explanation to figure this out? Thanks for the help! Sorry my english is not very good.