Adaptive Moving Average Kauffman

["Luca Meroni" <luca.meroni@xxxx>]

Hi at all.
I'm new with AB, but i find it very very 
good.
The AFL language is very nice, and I try to learn 
it.
I have the Adaptive Moving Average Kauffman formula 
for metastock:
 
 
Periods := Input("Time Periods",1,1000, 10);
Direction := CLOSE - Ref(Close,-periods);
Volatility := Sum(Abs(ROC(CLOSE,1,$)),periods);
ER := Abs(Direction/Volatility);
FastSC := 2/(2 + 1);
SlowSC := 2/(30 + 1);
SSC := ER * (FastSC - SlowSC) + SlowSC;
Constant := Pwr(SSC,2);
AMA := If(Cum(1) = periods +1, ref(Close,-1) + constant * (CLOSE - 
ref(Close,-1)),Prev + constant * (CLOSE - PREV));
AMA
How can I tranlate in AFL ?
 
Thanks, 
Luca