title: How can I divide each row of a matrix by a fixed row?
body: <p>Suppose I have a matrix like:</p>
  
  <pre><code>100 200 300 400 500 600
    1   2   3   4   5   6
   10  20  30  40  50  60
  ...
  </code></pre>
  
  <p>I wish to divide each row by the second row (each element by the corresponding element), so I'll get:</p>
  
  <pre><code>100 100 100 100 100 100
    1   1   1   1   1   1
   10  10  10  10  10  10
  ...
  </code></pre>
  
  <p>Hw can I do it (without writing an explicit loop)?</p>