Positive Volume Index

[JayF]

File Name: PVI_Peterson.efs

Description:
Positive Volume Index

Formula Parameters:
EMA_Len : 255

Notes:
The theory behind the indexes is as follows: On days of increasing volume,
you can expect prices to increase, and on days of decreasing volume, you can
expect prices to decrease. This goes with the idea of the market being in-gear
and out-of-gear. Both PVI and NVI work in similar fashions: Both are a running
cumulative of values, which means you either keep adding or subtracting price
rate of change each day to the previous day`s sum. In the case of PVI, if today`s
volume is less than yesterday`s, don`t add anything; if today`s volume is greater,
then add today`s price rate of change. For NVI, add today`s price rate of change
only if today`s volume is less than yesterday`s.


Download File:
PVI_Peterson.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:        
    Positive Volume Index
    
Version:            2.0  05/28/2009
 
Formula Parameters:                     Default:
    EMA_Len                             255
    
Notes:
    The theory behind the indexes is as follows: On days of increasing volume, 
    you can expect prices to increase, and on days of decreasing volume, you can 
    expect prices to decrease. This goes with the idea of the market being in-gear 
    and out-of-gear. Both PVI and NVI work in similar fashions: Both are a running 
    cumulative of values, which means you either keep adding or subtracting price 
    rate of change each day to the previous day`s sum. In the case of PVI, if today`s 
    volume is less than yesterday`s, don`t add anything; if today`s volume is greater, 
    then add today`s price rate of change. For NVI, add today`s price rate of change 
    only if today`s volume is less than yesterday`s.
**********************************/
var fpArray = new Array();
var bInit = false;

function preMain(){
    setStudyTitle("Positive Volume Index");
    setCursorLabelName("PVI",0);
    setDefaultBarFgColor(Color.red,0);
    setCursorLabelName("EMA",1);
    setDefaultBarFgColor(Color.blue,1);
    var x = 0;
    fpArray[x] = new FunctionParameter("EMA_Len", FunctionParameter.NUMBER);
    with(fpArray[x++]) {
        setLowerLimit(1);
        setDefault(255);
    }    
}

var xPVI = null;
var xPVI_EMA = null;

function main(EMA_Len) {
var nBarState = getBarState();
var nPVI = 0;
var nEMA = 0;
    if (nBarState == BARSTATE_ALLBARS) {
        if(EMA_Len == null) EMA_Len = 255;
    }
    if (bInit == false) {
        xPVI = efsInternal("Calc_PVI");
        xPVI_EMA = ema(EMA_Len, xPVI);
        bInit = true;
    }
    nPVI = xPVI.getValue(0);
    nEMA = xPVI_EMA.getValue(0);
    if (nEMA == null) return;
    return new Array(nPVI, nEMA);
}

var bSecondInit = false;
var xROC = null;
var xVolume = null;

function Calc_PVI() {
var nRes = 0;
var nRef = ref(-1);
    if (bSecondInit == false) {
        xROC = roc(1);
        xVolume = volume();
        bSecondInit = true;
    }
    if (xROC.getValue(-1) == null) return;
    if(xVolume.getValue(0) > xVolume.getValue(-1)) {
        nRes = nRef + xROC.getValue(0);    
    } else {
        nRes = nRef;
    }    
    return nRes;
}