title: How to quantize the values of tf.Variables in Tensorflow
body: <p>I have a training model like</p>
  
  <pre><code>Y = w * X + b
  </code></pre>
  
  <p>where Y and X are output and input placeholder, w and b are the vectors<br>
  I already know the value of w can only be 0 or 1, while b is still tf.float32.<br><br>
  How could I quantize the range of variable w when I define it?<br>
  or<br>
  Can I have two different learning rates? The rate for w is 1 or -1 and the rate for b is 0.0001 as usual.<br></p>