title: Create element-wise product of matrix columns
body: <pre><code>x1  x2  x3  x11 x12 x13 x22 x23 x33
  1   5   9   1   5   9   25  45  81
  2   6   10  4   12  20  36  60  100
  3   7   11  9   21  33  49  77  121
  4   8   12  16  32  48  64  96  144
  </code></pre>
  
  <p>When <code>x1</code>, <code>x2</code>, and <code>x3</code> are given, I would like to create a matrix or data frame <code>x11, x12, x13, x22, x23</code>, and <code>x33</code> which are element-wise product of vectors <code>x1, x2</code>, and <code>x3</code>.</p>
  
  <p>Actually I would like to to this for more vectors (e.g. <code>x1 ~ x6</code>) to high order (3rd or 4th).
  Is there an R command which can do this?</p>