The Quest For Reliable Crossovers for Amibroker (AFL)

_SECTION_BEGIN("The Quest For Reliable Crossovers");
function ZeroLagTEMA( array, period )
{
 TMA1 = TEMA( array, period );
 TMA2 = TEMA( TMA1, period );
 Diff = TMA1 - TMA2;
 return TMA1 + Diff ;
}
/////////////////////
// Heikin-Ashi code
HaClose = (O+H+L+C)/4;
HaOpen = AMA( Ref( HaClose, -1 ), 0.5 );
HaHigh = Max( H, Max( HaClose, HaOpen ) );
HaLow = Min( L, Min( HaClose, HaOpen ) );
// Velvoort is using not original, but modified Heikin-Ashi close
HaClose = ( HaClose + HaOpen + HaHigh + HaLow )/4;
// you can switch between Heikin-Ashi chart and regular candlestick chart
if( ParamToggle("Plot Heikin-Ashi", "No,Yes", 1 ) )
   PlotOHLC( HaOpen, HaHigh, HaLow, HaClose, "Heikin Ashi " + Name(), colorRose, styleCandle );
else
   Plot( C, "Regular candles " + Name(), colorRose, styleCandle );
period = Param("Avg. TEMA period", 55, 1, 100 );
ZLHa = ZeroLagTEMA( HaClose, period );
ZLTyp = ZeroLagTEMA( Avg, period );
Plot( ZLHa, "ZLTema(Ha,"+period+")", colorRed );
Plot( ZLTyp, "ZLTema(Typ,"+period+")", colorGreen );
Buy = Cross( ZLTyp, ZLHa );
Sell = Cross( ZLHa, ZLTyp );
PlotShapes( shapeUpArrow * Buy, colorGreen, 0, HaLow );
PlotShapes( shapeDownArrow * Sell, colorRed, 0, HaHigh );
_SECTION_END();