Ergotic MDI Strategy

////////////////////////////////////////////////////////////
//  Copyright by HPotter v1.0 17/07/2014
// This is one of the techniques described by William Blau in his book "Momentum,
// Direction and Divergence" (1995). If you like to learn more, we advise you to
// read this book. His book focuses on three key aspects of trading: momentum, 
// direction and divergence. Blau, who was an electrical engineer before becoming 
// a trader, thoroughly examines the relationship between price and momentum in 
// step-by-step examples. From this grounding, he then looks at the deficiencies 
// in other oscillators and introduces some innovative techniques, including a 
// fresh twist on Stochastics. On directional issues, he analyzes the intricacies 
// of ADX and offers a unique approach to help define trending and non-trending periods.
////////////////////////////////////////////////////////////
study(title="Ergotic MDI (Mean Deviation Indicator) Strategy")
r = input(32, minval=1)
s = input(5, minval=1)
u = input(5, minval=1)
SmthLen = input(3, minval=1)
hline(0, color=blue, linestyle=line)
xEMA = ema(close, r)
xEMA_S = close - xEMA
xEMA_U = ema(ema(xEMA_S, s), u)
xSignal = ema(xEMA_U, u)
pos =	iff(xEMA_U > xSignal, 1,
	    iff(xEMA_U < xSignal, -1, nz(pos[1], 0))) 
barcolor(pos == -1 ? red: pos == 1 ? green : blue )
plot(xEMA_U, color=green, title="Ergotic MDI")
plot(xSignal, color=red, title="SigLin")