title: Create a regular sequence of date-times (POSIXct) using seq()
body: <p>My goal is to create a vector of POSIXct time stamps given a start, an end and a delta (15min, 1hour, 1day). I hoped I could use <code>seq</code> for this, but I have a problem converting between the numeric and POSIXct representation:</p>
  <pre><code>now &lt;- Sys.time()
  now
  # [1] &quot;2012-01-19 10:30:39 CET&quot;
  as.POSIXct(as.double(now), origin=&quot;1970-01-01&quot;, tz=&quot;CET&quot;)
  # [1] &quot;2012-01-19 09:30:39 CET&quot;
  as.POSIXct(as.double(now), origin=as.POSIXct(&quot;1970-01-01&quot;, tz=&quot;CET&quot;), tz=&quot;CET&quot;)
  # [1] &quot;2012-01-19 09:30:39 CET&quot;
  </code></pre>
  <p>One hour gets lost during this conversion. What am I doing wrong?</p>