AFL Library

This is read-only version of AFL library entry. Ability to add user formulas and comment is only available from members-only area.

Details:

DISCLAIMER: Most formulas present in AFL on-line library are submitted by the users and are provided here on an "as is" and "as available" basis. AmiBroker.com makes no representations or warranties of any kind to the contents or the operation of material presented here. We do not maintain nor provide technical support for 3rd party formulas.
Description:

The Volatility System after Welles Wilder Jr
Book: New concepts in technical trading systems, 1978

Simple stop and reverse system. Did not see one single system designed by Wilder that actually works. We are so lucky having Amibroker and todays power of desktop computers.

Formula:

/*

The Volatility System after Welles Wilder Jr
Book: New concepts in technical trading systems, 1978

Translation in Amibroker Formula Language (AFL)
by: Edward Pottasch, empottasch@home.nl
created: October 18, 2004

*/

SetBarsRequired(100000,100000);

// setting for use in portfolio trading
SetOption("MaxOpenPositions", 25 ); 
PositionSize = -15;
SetTradeDelays(0,0,0,0);
PositionScore = 50 - RSI(14);

// constant (any number between 2.80 and 3.10)
const = 3.0; //const = Optimize("const", const, 0.5, 5, 0.1 );

// period over which ATR is calculated
period = 7; //period = Optimize("period", period, 1, 50, 1 );

// ARC
ARC = const * ATR(period);

// SIC (significant close) + / - ARC
SAR_long = Ref(HHV(C,period) - ARC,-1);
SAR_short = Ref(LLV(C,period) + ARC,-1);

// initialize storage array
SAR_plot = 0;
Buy = Short = Sell = Cover = 0;

// initialize position
lpos = 0;
spos = 0;

//
for (i = 0; i < BarCount; i++) {

	if (lpos == 0 AND spos == 0) {

		if (C[ i ] < SAR_long[ i ]) {
	
			Short[ i ] = 1;
			ShortPrice[ i ] = C[ i ];
			spos = 1;
		
		} else if (C[ i ] > SAR_short[ i ]) {

			Buy[ i ] = 1;
			BuyPrice[ i ] = C[ i ];
			lpos = 1;

		}	
		
		SAR_plot[ i ] = null;
	
	} else if (lpos == 1 AND spos == 0) {
	
		// update SAR for chart
		SAR_plot[ i ] = SAR_long[ i ];
		
		// check if we need to reverse
		if (C[ i ] < SAR_long[ i ]) {
	
			Sell[ i ] = 1;
			SellPrice[ i ] = C[ i ];
			lpos = 0;
			
			Short[ i ] = 1;
			ShortPrice[ i ] = C[ i ];
			spos = 1;
				
		}
	
	} else if (lpos == 0 AND spos == 1) {
	
		// update SAR for chart
		SAR_plot[ i ] = SAR_short[ i ];
		
		// check if we need to reverse
		if (C[ i ] > SAR_short[ i ]) {
	
			Cover[ i ] = 1;
			CoverPrice[ i ] = C[ i ];
			spos = 0;
			
			Buy[ i ] = 1;
			BuyPrice[ i ] = C[ i ];
			lpos = 1;
				
		}
		
	}

}


// Price chart
Plot(C,"",1,64);

// SAR (Stop and reverse points)
Plot(SAR_plot,"SAR", colorGold, styleDots | styleNoLine);

// buy, sell, short and cover symbols
PlotShapes(IIf(Buy,shapeUpArrow,0),colorWhite, layer = 0, yposition = BuyPrice,
offset = 0 );
PlotShapes(IIf(Sell,shapeDownArrow,0),colorYellow, layer = 0, yposition =
SellPrice, offset = 0 );
PlotShapes(IIf(Short,shapeHollowDownArrow,0),colorLightBlue, layer = 0,
yposition = ShortPrice, IIf(Sell,offset = -15,offset = 0) );
PlotShapes(IIf(Cover,shapeHollowUpArrow,0),colorGold, layer = 0, yposition =
CoverPrice, IIf(Buy,offset = -15,offset = 0) );

Comments: