[rrd-users] Quantisation issues - how do i get the math right?

Tobias Oetiker tobi at oetiker.ch
Fri Mar 10 15:10:54 CET 2017

if you have 'pulses' use the ABSOLUTE DS type ... 

and the multiply the result by whatever a pulse is worth 


----- On Mar 10, 2017, at 2:46 PM, Andreas Schuldei <andreas+rrdtool at schuldei.org> wrote: 

> This is a graph i get with my current intake of sun and my setup, consisting of
> thermo sensors on in- and outgoing water pipes, as well as a water meter,
> emitting S0 impulses, indicating that 10l of fluid were pumped.
> My Issue is with dealing with the impulses in a sensible way. The interval of
> these impulses varies, depending on the sun intake.

> currently my CDEF for the solar power is
> d,c,-,a,*,10,*,4.190,*
> where c and d are my temperatures, and a is my counter, indicating 10 liters.
> (4.190 is the specific heat constant of water.)

> Now what is calculated by that CDEF is not really the solar power, its the
> momentary value, only, calculated for the duration of the impulse, which is the
> width of my sampling rate (which is 10sec). it would have been more accurate to
> take the time between the impulses and calculate the incoming energy during
> that period, divided by the duration of that time and graph that for the
> previous (or following) interval.

> How can I do that?

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Tobi Oetiker, OETIKER+PARTNER AG, Aarweg 15 CH-4600 Olten, Switzerland 
www.oetiker.ch tobi at oetiker.ch +41 62 775 9902 
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