title: Plotting time series + offset not working
body: <p>I want to plot two time series that are in different formats in the
  same format, but one of those two doesn't work for me.</p>
  
  <p>So here's the thing: <br>
  I have a time series in seconds with a given starting time t0.</p>
  
  <p>So the series looks like this: <br>
  Starting time: t0</p>
  
  <p>0   -21.0028 <br>
  5   -21.0067 <br>
  10  -21.007  <br>
  ...          <br>
  17875   -20.9943 <br></p>
  
  <p>I want to plot this time series with the time (e.g. 9:03) instead
  of seconds and I want to show another time series where the
  data is given in standard time in the same plot.</p>
  
  <p>I can plot the second series just fine.
  But when I try to plot the first series, the measured points
  start jumping from x=100 back to 0 and then back and forth.
  Additionally I can't add the offset t0 to the series.</p>
  
  <p>Here's what I tried (t0 = 32615s) to get at least the first time series plotted:</p>
  
  <p>gnuplot> set xdata time <br>
  gnuplot> set timefmt "%S" <br>
  gnuplot> set format x "%H:%M" <br>
  gnuplot> plot 'measurement.dat' u (timecolumn(1)+32615):2 w l, 'measurement2.dat" u 1:2 w l <br></p>
  
  <p>Does anyone know how I can plot these time series?</p>
  
  <p>Thanks in advance!</p>