title: Matrix multiplication giving NA
body: <p>I'm attempting to do simple matrix multiplication, that has never given me this issue before. </p>
  
  <p>I have an X matrix (nxfe) and a matrix of observations, y (nx1). For the purposes of this example lets just say </p>
  
  <pre><code>X &lt;- matrix(c(1, 0, 0, 0, 0, 1, 0, 0, 0, 0, 1, 0, 0, 0, 0, 1), nrow=4)
  y &lt;- matrix(c(1, 2, 3, 4), nrow=4)
  </code></pre>
  
  <p>simple code for this multiplication is </p>
  
  <pre><code>Xt &lt;- t(X)
  Xy &lt;- Xt%*%y
  </code></pre>
  
  <p>however, when I do this, I get a matrix of NA's (nx1). </p>
  
  <p>This has never happened before. I have checked and there are appropriate values in all my matrices. Any help would be appreciated. </p>