title: .Machine$double.eps larger than necessary?
body: <p>The documentation describes <code>.Machine$double.eps</code> as <em>The smallest positive floating-point number x such that <code>1 + x != 1</code></em>. So I would expect the following to produce a 1:</p>
  
  <pre><code>options(digits=17)
  1 + .Machine$double.eps
  # [1] 1.0000000000000002
  </code></pre>
  
  <p>but it doesn't. It appears that I have to go as low as <code>0.5*.Machine$double.eps</code> before I get the expected round-off to one. Am I misunderstanding something about <code>.Machine$double.eps</code>? Is this platform-dependent? (sessionInfo() below)</p>
  
  <pre><code>&gt; sessionInfo()
  R version 3.0.2 (2013-09-25)
  Platform: x86_64-apple-darwin10.8.0 (64-bit)
  
  locale:
  [1] en_CA.UTF-8/en_CA.UTF-8/en_CA.UTF-8/C/en_CA.UTF-8/en_CA.UTF-8
  
  attached base packages:
  [1] stats     graphics  grDevices utils     datasets  methods   base     
  
  loaded via a namespace (and not attached):
  [1] tools_3.0.2
  </code></pre>
  
  <p>Thank you</p>