Simple moving average in RRD

It's quite easy to add simple moving average (SMA) to RRD with rrd PREV function.
PREV allows you to get data from previous time stamp. The magic is that you can run that function on sequences of variables to dig deeper in the past.

Here is SMA from 10 variables, current value and 9 from the past (php template for PNP).

$def[1] .= "DEF:idle=$rrdfile:$DS[3]:AVERAGE " ;

$def[1] .= "CDEF:idle1=PREV(idle), " ;
$def[1] .= "CDEF:idle2=PREV(idle1), " ;
$def[1] .= "CDEF:idle3=PREV(idle2), " ;
$def[1] .= "CDEF:idle4=PREV(idle3), " ;
$def[1] .= "CDEF:idle5=PREV(idle4), " ;
$def[1] .= "CDEF:idle6=PREV(idle5), " ;
$def[1] .= "CDEF:idle7=PREV(idle6), " ;
$def[1] .= "CDEF:idle8=PREV(idle7), " ;
$def[1] .= "CDEF:idle9=PREV(idle8), " ;
$def[1] .= "CDEF:idle_sma=idle,idle1,idle2,idle3,idle4,idle5,idle6,idle7,idle8,idle9,+,+,+,+,+,+,+,+,+,10,/ " ;