[rrd-users] NAN and 0 in aggregate graphs

[Alex van den Bogaerdt]

On Mon, Mar 31, 2008 at 02:07:54PM +0000, Simon Hobson wrote:
> Adam Jacob Muller wrote:
> 
> >Right now I am solving this by doing something like:
> >
> >CDEF:field1_nz=%s,UN,0,field1,IF
> >CDEF:field2_nz=%s,UN,0,field2,IF
> >CDEF:field_total=field1_nz,field2_nz,+
> >
> >this works, but, on values where both are NAN this returns 0, it would
> >be much more preferable to return NAN here
> 
> 
> Hmm, looking at the doc pages it doesn't look like boolean operators 
> (AND, OR) are provided,

er...

FALSE==0
TRUE==1  (in reality: TRUE==anything but 0)

          \
 x     y   \   +      *
------------+--------------
FALSE FALSE | FALSE  FALSE
FALSE TRUE  | TRUE   FALSE
TRUE  FALSE | TRUE   FALSE
TRUE  TRUE  | TRUE   TRUE

If you want: if (x and y) then B else C:

then use CDEF:   x,y,*,B,C,IF

(also see example in doc:  replace A by x,y,*)

-- 
Alex van den Bogaerdt
http://www.vandenbogaerdt.nl/rrdtool/