title: NA values not being excluded in `cor`
body: <p>To simplify, I have a data set which is as follows:</p>
  
  <pre><code>b &lt;- 1:6
  # &gt; b
  # [1] 1 2 3 4 5 6
  jnk &lt;- c(2, 4, 5, NA, 7, 9)
  # &gt; jnk
  # [1]  2  4  5 NA  7  9
  </code></pre>
  
  <p>When I try:</p>
  
  <pre><code>cor(b, jnk, na.rm=TRUE)
  </code></pre>
  
  <p>I get:</p>
  
  <pre><code>&gt; cor(b, jnk, na.rm=T)
    Error in cor(b, jnk, na.rm = T) : unused argument (na.rm = T)
  </code></pre>
  
  <p>I've also tried <code>na.action = na.exclude</code>, etc. None seem to work. It'd be really helpful to know what the issue is and how I can fix it. Thanks.</p>