[rrd-users] Re: Base for AREA plots

[Tobias Oetiker]

Today Christopher Snell wrote:

> Hi,
>
> I'm trying to do an AREA plot on a graph measuring temperature (in
> Celcius).  Does anyone know how to make the AREA function fill from x
> -> value, where x is < 0, instead of from 0 -> value?  I would like to
> set my baseline at -20 and plot my AREA for any value about -20.   I
> realize that AREA, when given a negative number, will draw from 0
> downward to that number.  Instead, I want it to draw from a my
> baseline number (-20) upwards.

Hi Chris,

you could use CDEF to establish a value which is constantly -20
draw this as AREA and then use STACK for the actual temperature ...

note that CDEF needs at least one variable, but you can eliminate
its content by multiplying it with 0 or some other math op ...

cheers
tobi

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