Demand Index - tweaked

/*********************************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:           Demand Index - tweakedVersion:            1.0  11/10/2008Formula Parameters:                     Default:    Length                               5Notes:    The Demand Index, developed by James Sibbet, combines price and volume    in such a way that it is often a leading indicator of price change.     The Demand Index calculations are too complex, however, for this text.     The calculations require 21-column accounting paper to calculate manually.    **********************************/var fpArray = new Array();var bInit = false;function preMain(){    setStudyTitle("Demand Index - tweaked");    setCursorLabelName("Demand Index", 0);    setDefaultBarFgColor(Color.blue, 0);    addBand(0, PS_SOLID, 1, Color.black);        var x=0;    fpArray[x] = new FunctionParameter("Length", FunctionParameter.NUMBER);	with(fpArray[x++]){        setLowerLimit(1);		        setDefault(5);    }}var xTR = null;var xAvgTR = null;var nBuyPres_1 = 1;var nSellPres_1 = 1;var nSellPres = 1;var nBuyPres = 1;var nVolAvg_1 = 0;var nVolAvg = 0;var nWghtClose_1 = 0;var nWghtClose = 0;function main(Length) {var nWtCRatio = 1;var nVolRatio = 1;var nBuyP = 1;var nSellP = 1;var nSign = 1;var nConstant = 1;var nTempDI = 1;var nDMI = 1;var nState = getBarState();       if (nState == BARSTATE_ALLBARS) {        if(Length == null)	Length = 5;	}	    if (nState == BARSTATE_NEWBAR) {        nBuyPres_1 = nBuyPres;        nSellPres_1 = nSellPres;        nVolAvg_1 = nVolAvg;        nWghtClose_1 = nWghtClose;	}    if ( bInit == false ) {         xTR = efsInternal("TrueRange");        xAvgTR = sma(Length, xTR);        bInit = true;     }     if (getCurrentBarCount() < Length) return;	nWghtClose = (high(0) + low(0) + 2 * close(0)) * 0.25;    nVolAvg = ((nVolAvg_1 * (Length - 1)) + volume(0)) / Length;	if (nWghtClose != 0 && nWghtClose_1 != 0) {		nWtCRatio = (nWghtClose - nWghtClose_1) / Math.min(nWghtClose, nWghtClose_1);        	nVolRatio = volume(0) /  nVolAvg;       	nConstant = ((nWghtClose * 3) / xAvgTR.getValue(0)) * Math.abs(nWtCRatio); 		if(nConstant > 88)			nConstant = 88;		nConstant = nVolRatio / Math.exp(nConstant);       	if(nWtCRatio > 0){            nBuyP = nVolRatio;        	    nSellP = nConstant;        	} else {            nBuyP = nConstant;       	    nSellP = nVolRatio;        	}		nBuyPres = ((nBuyPres_1 * (Length - 1)) + nBuyP) / Length;        	nSellPres = ((nSellPres_1 * (Length - 1)) + nSellP) / Length; 		nTempDI = +1;        	if(nSellPres  > nBuyPres){            nSign  =  -1;        	    if(nSellPres != 0)      	    	nTempDI = nBuyPres / nSellPres;         } else {            nSign  =  +1;           	if(nBuyPres != 0)           	  	nTempDI = nSellPres / nBuyPres;         }		nTempDI = nTempDI * nSign;         if(nTempDI < 0)	        nDMI = -1 - nTempDI;         else           	nDMI = +1 - nTempDI; 	}	    return nDMI; }function TrueRange(){    return Math.max((high(0)-low(0)),Math.abs(close(-1)-high(0)),Math.abs(close(-1)-low(0)));}