The Center Of Gravity

Gravity.efs  
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File Name: Gravity.efs

Description:
The Center Of Gravity

Formula Parameters:

• Length : 10

Notes:

This indicator identifies every major turning point without much lag.
This indicator is computed in a similiar way to the Ehlers filter.
The position of the balance point is the summation of the product of position within the observation window multiplied by the price at that position divided by the summation of prices across the window. The formula is:

CG = SUM(x+1) * Price(i) / SUMPrice(i)

In this formula "1" is added to the position count because it starts with the most recent price at zero, and multiplying the most recent price by that position count would remove it from the computation.

Download File:
Gravity.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:        
    The Center Of Gravity
    
Version:            1.0  05/05/2009
    
Formula Parameters:                     Default:
    Length                              10

Notes:
    This indicator identifies every major turning point without much lag. 
    This indicator is computed in a similiar way to the Ehlers filter. 
    The position of the balance point is the summation of the product of 
    position within the observation window multiplied by the price at that 
    position divided by the summation of prices across the window. The formula is:
    CG = SUM(x+1) * Price(i) / SUMPrice(i)
    In this formula "1" is added to the position count because it starts with 
    the most recent price at zero, and multiplying the most recent price by that 
    position count would remove it from the computation. 
**********************************/
var fpArray = new Array();
var bInit = false;

function preMain() {
	setStudyTitle("Center of Gravity Oscillator");
    setCursorLabelName("Gravity", 0);	
    setCursorLabelName("Temp", 1);	    
	setPriceStudy(false);
	setDefaultBarFgColor(Color.red, 1);
	setDefaultBarFgColor(Color.blue, 0);
    var x = 0;
    fpArray[x] = new FunctionParameter("Length", FunctionParameter.NUMBER);
    with(fpArray[x++]) {
        setLowerLimit(1);
        setDefault(10);
    }
}

var xGravity = null;

function main(Length) {
var nBarState = getBarState();
var nGravity = 0;
var nTemp = 0;
    if (nBarState == BARSTATE_ALLBARS) {
        if(Length == null) Length = 10;
    }    
    if (bInit == false) {
        xGravity = efsInternal("Calc_Gravity", Length);
        bInit = true;
    }
    nGravity = xGravity.getValue(0);
    nTemp =  xGravity.getValue(-1);
    if (nTemp == null) return;
    return new Array(nGravity, nTemp);
}

var bSecondInit = false;
var xHL2 = null;

function Calc_Gravity(Length) {
var nRes = 0;
var i = 0;
var nHL2 = 0;
var num = 0;
var denom = 0;
    if (bSecondInit == false) {
        xHL2 = hl2();
        bSecondInit = true;
    }
    if (xHL2.getValue(-Length) == null) return;
    for(i = 0; i < Length; i++) {
        nHL2 = xHL2.getValue(-i);
        num += (1 + i) * nHL2;
        denom += nHL2;
    }
    if(denom != 0) 	nRes = - num / denom;
    return nRes;
}