Hi,
 
Is there any way to subtract two graph from each other on a third graph?
 
example:
 
[foo.org]
   address 1.1.1.1
 
[bar.org]
   address 2.2.2.2
 
[foobar.org]
   update no
 
   power.update no
   power.graph_order power_sub
   power.graph_title Power Sub
   power.graph_vlabel kW
   power.power_sub.label Power Sub
   power.power_sub.sum foo.org:power.total_power bar.org:ups.total_power.cdef 0,total_power,-
 
Thanks for help!