title: Results with difftime in R different from excel and timeanddate.com
body: <pre><code>t1 &lt;- strptime("2015-02-17 12:20:00", format = "%Y-%m-%d %H:%M:%S", tz = "America/Chicago")
  t2 &lt;- strptime("2015-03-13 15:00:00", format = "%Y-%m-%d %H:%M:%S", tz = "America/Chicago")
  as.numeric(abs(difftime(t1, t2, units = "mins", tz = "America/Chicago")))
  </code></pre>
  
  <p>The above returns 34,660 while Excel and <a href="http://www.timeanddate.com/date/duration.html" rel="nofollow">http://www.timeanddate.com/date/duration.html</a> both return 34,720.  R recognizes t1 as CST and t2 as CDT due to daylight savings on 3/8/15.  I wanted to confirm that R is correct, while these other two sources are not.</p>