[rrd-users] rpn to convert NaN to 0

Mark Hedges mark at phix.me
Sat Mar 14 20:13:35 CET 2009

I think Alex is meaning this tutorial:


There are examples on that (around the middle of the page).

I'm not sure why you are now getting nothing graphed. I would only use
the IF/UN RPN statement on the value you know that could be NaN and
just customise it as you see fit.

I recently had to use this method to some across more than 100
different values, any of which could have been NaNs - produced a very
lengthy RPN expression.


2009/3/14 R Dicaire <kritek at gmail.com>:
> On Sat, Mar 14, 2009 at 2:44 PM,  <parkamark at gmail.com> wrote:
>> CDEF:ices=icecast,UN,0,icecast,IF,vicecast,UN,0,vicecast,IF,+
> Hi Mark, while this one doesn't error when creating the graph, the
> result isn't graphed.
> icecast will always return a num since its always running, vicecast is
> the one that that may return NaN.
> If I read your CDEF correctly, UN is the NaN? And reads as if vicecast
> is UN then set to 0?
> What purpose does iterating icecast and vicecast a second time in the
> statement achieve?
> Alex, if you're referring to
> http://oss.oetiker.ch/rrdtool/tut/rpntutorial.en.html, there's no
> mention of converting NaN to 0, the tutorial assumes all values are
> valid, but thanks.
> --
> aRDy Music and Rick Dicaire present:
> http://www.ardynet.com
> http://www.ardynet.com:9000/ardymusic.ogg.m3u

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