Kaufman's Adaptive Moving Average I

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