Ergotic MDI (Mean Deviation Indicator)

/*********************************Provided By:      eSignal (Copyright c eSignal), a division of Interactive Data     Corporation. 2008. All rights reserved. This sample eSignal     Formula Script (EFS) is for educational purposes only and may be     modified and saved under a new file name.  eSignal is not responsible    for the functionality once modified.  eSignal reserves the right     to modify and overwrite this EFS file with each new release.Description:            Ergotic MDI (Mean Deviation Indicator)    Version:            1.0  01/12/2009Formula Parameters:                     Default:    r                                   32    s                                   5        u                                   5    Notes:    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.**********************************/var fpArray = new Array();var bInit = false;function preMain() {    setStudyTitle("Ergotic_MDI (Mean Deviation Indicator)");    setCursorLabelName("ErgMDI", 0);    setCursorLabelName("SigLin", 1);    setDefaultBarFgColor(Color.fushcia, 0);    setDefaultBarFgColor(Color.grey, 1);    addBand(0, PS_SOLID, 1, Color.blue);        var x=0;    fpArray[x] = new FunctionParameter("r", FunctionParameter.NUMBER);	with(fpArray[x++]){        setLowerLimit(1);		        setDefault(32);    }    fpArray[x] = new FunctionParameter("s", FunctionParameter.NUMBER);	with(fpArray[x++]){        setLowerLimit(1);		        setDefault(5);    }    fpArray[x] = new FunctionParameter("u", FunctionParameter.NUMBER);	with(fpArray[x++]){        setLowerLimit(1);		        setDefault(5);    }}var xSignal = null;var xEMA_R = null;var xEMA_S = null;var xEMA_U = null;function main(r, s, u) {var nState = getBarState();var nMDI = 0;var nSignal = 0;    if (nState == BARSTATE_ALLBARS) {        if (r == null) r = 32;        if (s == null) s = 5;        if (u == null) u = 5;    }    if ( bInit == false ) {         xEMA = ema(r);        xEMA_S = efsInternal("Calc_EMA_S", xEMA);        xEMA_U = ema(u, ema(s, xEMA_S));        xSignal = ema(u, xEMA_U);        bInit = true;     }     nMDI = xEMA_U.getValue(0);    nSignal = xSignal.getValue(0);        if (nSignal == null || nMDI == null) return;    return new Array(nMDI, nSignal);}function Calc_EMA_S(xEMA) {var nRes = 0;    if (xEMA.getValue(0) == null) return;    nRes = close(0) - xEMA.getValue(0);    if (nRes == null) nRes = 1;    return nRes;}