D_ELI (Ehlers Leading Indicator)

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//  Copyright by HPotter v1.0 17/04/2014
// This Indicator plots a single
// Daily DSP (Detrended Synthetic Price) and a Daily ELI (Ehlers Leading
// Indicator) using intraday data.
// Detrended Synthetic Price is a function that is in phase with the dominant
// cycle of real price data. This one is computed by subtracting a 3 pole Butterworth
// filter from a 2 Pole Butterworth filter. Ehlers Leading Indicator gives an advanced
// indication of a cyclic turning point. It is computed by subtracting the simple
// moving average of the detrended synthetic price from the detrended synthetic price.
// Buy and Sell signals arise when the ELI indicator crosses over or under the detrended
// synthetic price.
// See "MESA and Trading Market Cycles" by John Ehlers pages 64 - 70. 
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study(title="D_ELI (Ehlers Leading Indicator)", shorttitle="D_ELI (Ehlers Leading Indicator)")
Length = input(7, minval=1)
hline(0, color=red, linestyle=line)
xHL2 = security(tickerid, 'D', hl2)
xEMA1 = ema(xHL2, Length)
xEMA2 = ema(xHL2, 2 * Length)
xEMA1_EMA2 = xEMA1 - xEMA2
xResultEMA = ema(xEMA1_EMA2, Length)
nRes = xEMA1_EMA2 - xResultEMA
plot(security(tickerid, "D", xEMA1_EMA2), color=blue, title="D_DSP")
plot(security(tickerid, "D", nRes), color=green, title="D_ELI")