title: demean and intercept in ar.ols()
body: <p>The prototype of ar.ols() is</p>
  
  <pre><code>ar.ols(x, aic = TRUE, order.max = NULL, na.action = na.fail,
              demean = TRUE, intercept = demean, series, ...)
  
  demean: should the AR model be for ‘x’ minus its mean?
  
  intercept: should a separate intercept term be fitted?
  </code></pre>
  
  <p>I wonder what differences are between demean and intercept? Thanks!</p>