title: what's meaning of function predict's returned value in OpenCV?
body: <p>I use function <code>predict</code> in opencv to classify my gestures.</p>
  
  <pre><code>svm.load("train.xml");
  float ret = svm.predict(mat);//mat is my feature vector
  </code></pre>
  
  <p>I defined 5 labels <code>(1.0,2.0,3.0,4.0,5.0)</code>, but in fact the value of ret are <code>(0.521220207,-0.247173533,-0.127723947······)</code></p>
  
  <p>So I am confused about it. As Opencv official document, the function returns a class label (classification) in my case.</p>
  
  <p>update: I don't still know why to appear this result. But I choose new features to train models and the return value of predict function is what I defined during train phase (e.g. 1 or 2 or 3 or etc).</p>