title: How to stack multiple matrices in R
body: <p>I have a list of matrices, similar to the one obtained by the code below:</p>
  
  <pre><code>a &lt;- matrix(1, ncol=2, nrow=3)
  b &lt;- matrix(2, ncol=2, nrow=3)
  c &lt;- matrix(3, ncol=2, nrow=3)
  d &lt;- list(a, b, c)
  </code></pre>
  
  <p>I want to stack them so that they are in one matrix, similar to this one:</p>
  
  <pre><code>e &lt;- rbind(d[[1]], d[[2]], d[[3]])
  </code></pre>
  
  <p>The trick is that I don't know in advance how many matrices will need to be joined.  Is there a good way to write code that will stack all matrices in the list?</p>