title: Detect signal jumps relative to local activity
body: <p>In Matlab, is it possible to measure local variation of a signal across an entire signal without using <code>for</code> loops? I.e., can I implement the following:</p>
  
  <pre><code>window_length = &lt;something&gt;
  for n = 1:(length_of_signal - window_length/2)
      global_variance(n) = var(my_signal(1:window_length))
  end
  </code></pre>
  
  <p>in a vectorized format?</p>