2017 Sep: The Reverse EMA Indicator by John F. Ehlers

[eSignal]

File Name: Reverse_EMA.efs

Description:
The Reverse EMA Indicator by John F. Ehlers

Formula Parameters:

Reverse_EMA.efs

Alpha: 0.1

Notes:
The related article is copyrighted material. If you are not a subscriber
of Stocks & Commodities, please visit www.traders.com.

Download File:
Reverse_EMA.efs


Reverse_EMA.efs


EFS Code:

/*********************************
Provided By:  
eSignal (Copyright c eSignal), a division of Interactive Data
Corporation. 2016. 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:        
    The Reverse EMA Indicator by John F. Ehlers

Version:            1.00  07/12/2017

Formula Parameters:                     Default:
Alpha                                   0.1



Notes:
The related article is copyrighted material. If you are not a subscriber
of Stocks & Commodities, please visit www.traders.com.

**********************************/

var fpArray = new Array();

function preMain(){
    setPriceStudy(false);

    var x=0;
    fpArray[x] = new FunctionParameter("Alpha", FunctionParameter.NUMBER);
    with(fpArray[x++]){
        setName("Alpha Value");
        setDefault(0.1);
        setLowerLimit(0);
        }
}

var bInit = false;
var bVersion = null;

var xClose = null;

var xEMA = null;
var xRevEMA = null;

function main (Alpha){
    if (bVersion == null) bVersion = verify();
    if (bVersion == false) return;

    var nLength = ((2 / Alpha) - 1) * 3;

    if (getCurrentBarCount() < nLength) return;

    if (getBarState() == BARSTATE_ALLBARS){
        bInit = false;
    }

    if (!bInit){
        xClose = close();

        xEMA = efsInternal("calc_EMA", Alpha, xClose);
        xRevEMA = efsInternal("calc_RevEMA", (1 - Alpha), 1, xEMA);

        var power = 2;

        for (var i = 0; i < 7; i++){
            xRevEMA = efsInternal("calc_RevEMA", (1 - Alpha), power, xRevEMA);
            power *= 2;

        }

        addBand(0, PS_DASH, 1, Color.grey, 1);

        bInit = true;
    }

    if (xRevEMA.getValue(0) != null){
        return (xEMA.getValue(0) - 0.1 * xRevEMA.getValue(0));
    }
}

function calc_EMA(nAA, xSeries){
    var nEMA_1 = ref(-1);
    if (nEMA_1 == null) nEMA_1 = 0;
    var nEMA = ((xSeries.getValue(0) - nEMA_1) * nAA) + nEMA_1;

    if (nEMA != null) return nEMA;
}

function calc_RevEMA(nCC, power, xSeries){
    if (xSeries.getValue(-1) == null) return;
    var nRevEMA = Math.pow(nCC, power) * xSeries.getValue(0) + xSeries.getValue(-1);

    if (nRevEMA != null) return nRevEMA;
}

function verify(){
    var b = false;
    if (getBuildNumber() < 779){
        drawTextAbsolute(5, 35, "This study requires version 10.6 or later.",
            Color.white, Color.blue, Text.RELATIVETOBOTTOM|Text.RELATIVETOLEFT|Text.BOLD|Text.LEFT,
            null, 13, "error");
        drawTextAbsolute(5, 20, "Click HERE to upgrade.@URL=http://www.esignal.com/download/default.asp",
            Color.white, Color.blue, Text.RELATIVETOBOTTOM|Text.RELATIVETOLEFT|Text.BOLD|Text.LEFT,
            null, 13, "upgrade");
        return b;
    }
    else
        b = true;

    return b;
}