title: Multi-timeseries operations in Grafana
body: <p>How do I subtract two timeseries in <a href="http://grafana.org/" rel="noreferrer">Grafana</a>?  Or add two together, divide one by another, etc...?  I have found vague hints online about taking differences between timeseries, but nothing that actually tells me how to do so.  I'm using Grafana <code>v2.0.2</code> with Influxdb <code>v0.8</code> and have played around with the graph controls enough to discover things like the <code>difference</code> operator I can apply, but I have no idea how to use it.  I've attempted to find documentation on this, but the <a href="http://docs.grafana.org/datasources/influxdb/" rel="noreferrer">closest I can find</a> is pretty much silent on this topic, and also looks to be slightly out of date, as the interface has changed since those screenshots were taken.</p>
  
  <p>Thanks!</p>