How to take derivative of a sum of series

Asked by Jens Rantil on 2014-12-11

I have a couple of series of monotonically increasing values as a function of time. In other words, counters. I would like to graph the (non-negative) derivative of the sum of these series. Can I do that?

So far I have tried:

sumSeries(nonNegativeDerivative(my.series.*.count))

and

nonNegativeDerivative(sumSeries(my.series.*.count))

Neither of these works. Am I using the wrong functions? Can this be done?

Question information

Language:
English Edit question
Status:
Solved
For:
Graphite Edit question
Assignee:
No assignee Edit question
Solved by:
Jens Rantil
Solved:
2014-12-11
Last query:
2014-12-11
Last reply:
Denis Zhdanov (deniszhdanov) said : #1

Hi Jens,

Usually you are need to use sumSeries(nonNegativeDerivative()) instead of vice versa - but main reason behind it is spikes - see http://www.jilles.net/perma/2013/08/22/how-to-do-graphite-derivatives-correctly/ for details. If you have no gaps in graphs both of them will work fine.

Jens Rantil (jens-rantil) said : #2

Good call. I had non-continuous data that made the derivate break. Will see if correcting my retention policies can help here...