title: What is `lr_policy` in Caffe?
body: <p>I just try to find out how I can use <a href="http://caffe.berkeleyvision.org/">Caffe</a>. To do so, I just took a look at the different <code>.prototxt</code> files in the examples folder. There is one option I don't understand:</p>
  
  <pre><code># The learning rate policy
  lr_policy: "inv"
  </code></pre>
  
  <p>Possible values seem to be:</p>
  
  <ul>
  <li><code>"fixed"</code></li>
  <li><code>"inv"</code></li>
  <li><code>"step"</code></li>
  <li><code>"multistep"</code></li>
  <li><code>"stepearly"</code></li>
  <li><code>"poly"</code>  </li>
  </ul>
  
  <p>Could somebody please explain those options?</p>