Trend Analysis Index (TAI)

TAI.efs  
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File Name: TAI.efs

Description:
Trend Analysis Index (TAI)

Formula Parameters:

• AvgLen : 28
• TAILen : 5
• Source of TAI : Close

Notes:
In essence, it is simply the standard deviation of the last x bars of a y-bar moving average. Thus, the TAI is a simple trend indicator when prices trend with authority, the slope of the moving average increases, and when prices meander in a trendless range, the slope of the moving average decreases.

Download File:
TAI.efs


EFS Code:

/*********************************
Provided By:  
    eSignal (Copyright c eSignal), a division of Interactive Data 
    Corporation. 2009. 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:        
    Trend Analysis Index
    
Version:            1.0  05/20/2009
     
Formula Parameters:                     Default:
    AvgLen                              28
    TAILen                              5
    Source of TAI                       Close
    
Notes:
    In essence, it is simply the standard deviation of the last x bars of a 
    y-bar moving average. Thus, the TAI is a simple trend indicator when prices 
    trend with authority, the slope of the moving average increases, and when 
    prices meander in a trendless range, the slope of the moving average decreases.
**********************************/
var fpArray = new Array();
var bInit = false;

function preMain() {
    setPriceStudy(false);
    setStudyTitle("Trend Analysis Index");
    setCursorLabelName("TAI");
    var x = 0;
    fpArray[x] = new FunctionParameter("AvgLen", FunctionParameter.NUMBER);
    with(fpArray[x++]) {
        setLowerLimit(1);
        setDefault(28);
    }    
    fpArray[x] = new FunctionParameter("TAILen", FunctionParameter.NUMBER);
    with(fpArray[x++]) {
        setLowerLimit(1);
        setDefault(5);
    }    
    fpArray[x] = new FunctionParameter("sPrice", FunctionParameter.STRING);
	with(fpArray[x++]){
        setName("Source of TAI");
        addOption("open"); 
        addOption("high");
        addOption("low");
        addOption("close");
        addOption("hl2");
        addOption("hlc3");
        addOption("ohlc4"); 
        setDefault("close"); 
    }    
}

var xTAI = null;

function main(sPrice, AvgLen, TAILen) {
var nBarState = getBarState();
var nTAI = 0;
    if (nBarState == BARSTATE_ALLBARS) {
        if (sPrice == null) sPrice = "close";
        if (AvgLen == null) AvgLen = 28;
        if (TAILen == null) TAILen = 5;
    }
    if (bInit == false) {
        xTAI = efsInternal("Calc_TAI", sPrice, AvgLen, TAILen);
        bInit = true;
    }
    nTAI = xTAI.getValue(0);
    if (nTAI == null) return;
    return nTAI;
}

var bSecondInit = false;
var xSMA = null;
var xHH = null;
var xLL = null;
var xPrice = null;

function Calc_TAI(sPrice, AvgLen, TAILen) {
var nRes = 0;
    if (bSecondInit == false) {
        xPrice = eval(sPrice)();
        xSMA = sma(AvgLen, xPrice);
        xHH = upperDonchian(TAILen, xSMA);
        xLL = lowerDonchian(TAILen, xSMA);
        bSecondInit = true;
    }
    if (xHH.getValue(0) == null) return;
    nRes = (xHH.getValue(0) - xLL.getValue(0)) * 100 / xPrice.getValue(0);
    return nRes;
}