title: What are the interval transforms in pymc3 for uniform distributions?
body: <p>I've noticed that when using uniform distributions in pymc3, the sampler also scans over an <code>_interval</code> parameter as well unless a transform is specified for example:</p>
  
  <pre><code>with fitModel6:
  
      normMu  = pm.Uniform('normMu',lower=0,upper=1000)
  </code></pre>
  
  <p>will result in not only sampling over normMu, but also, normMu_interval:</p>
  
  <p><a href="http://i.stack.imgur.com/2gw5k.png" rel="nofollow">trace plot of interval</a></p>
  
  <p><a href="http://i.stack.imgur.com/IRiyc.png" rel="nofollow">trace plot of parameter</a></p>
  
  <p>Normally, when I am using an uniform prior for scale parameter like a normalization, I will of course sample over the log interval. Is pymc3 handling this for me somehow?</p>
  
  <p>Cheers</p>