High - EMA Strategy

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//  Copyright by HPotter v1.0 02/07/2014
// This indicator plots the difference between the High (of the previous period)
// and an exponential moving average (13 period) of the Close (of the previous period).
// You can use in the xPrice any series: Open, High, Low, Close, HL2, HLC3, OHLC4 and ect...
// It buy if indicator above 0 and sell if below.
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study(title="High - EMA Strategy", shorttitle="High - EMA Strategy")
Length = input(13, minval=1)
xPrice = close  // You can use any series
hline(0, color=red, linestyle=line)
xEMA = ema(xPrice, Length)
nRes = high[1] - nz(xEMA[1])
pos =	iff(nRes > 0, 1,
	    iff(nRes < 0, -1, nz(pos[1], 0))) 
barcolor(pos == -1 ? red: pos == 1 ? green : blue )
plot(nRes, color=blue, title="High - EMA")