EMA10 of Bollinger bandwidth

[rsy]

Hi!

I need some help to write an EFS that plots EMA10 of Bollinger Bandwidth.

Any?

RSy

[rsy]

Bollinger Bandwidth attached.

RSy

[eSignal_JasonK]

Hello RSy,

The study you are looking for can be found in our EFS Library. The default length is 20. You can change that through "Edit Studies" or you can change the default to 10 with the editor on line 48.

BollingerEMA.efs

[rsy]

JasonK, thanks, but it isn't BollingerEMA I am looking for, but the bandwidth and EMA of the bandwidth to be plotted.

RSy

[eSignal_JasonK]

Hello RSy,

So you want to see a total of four lines on the chart? The regular Bollinger Bands plus a 10 period EMA for both bands and no basis line. Is this correct?

[rsy]

No, just 2 lines. Not bollinger upper and lower, but the diffrence between upper and lower, and a EMA of that one.

RSy

[eSignal_JasonK]

Hello RSy,

Do you want this to be plotted as a price study or non-price study?

[xygeek]

It's a non price study that plots the range between BB's. Upper BB minus Lower BB. I can code that but RSY wants an EMA of that range.

It will be interesting to see how the EMA is done. Probably use an array of the previous values for range but where do we go from there to get the EMA?

[xygeek]

How can I add an EMA(10) to this?

/* Copyright © eSignal, a division of Interactive Data Corporation. 2003. All rights reserved. 
This sample eSignal Formula Script (EFS) may be modified and saved under a new 
filename; however, eSignal is no longer responsible for the functionality once modified.
eSignal reserves the right to modify and overwrite this EFS file with each new release. */

////////////////////////////////////////////////////
// BandWidth Study
/////////////////////////////////////////////////////

var bb = new BollingerStudy(20, "Close", 2.0);

function main() {
    var vUpper = bb.getValue(BollingerStudy.UPPER);
    var vLower = bb.getValue(BollingerStudy.LOWER);
    var vMiddle = bb.getValue(BollingerStudy.BASIS);
    
    if(vUpper == null || vLower == null || vMiddle == null)
        return;
        
    return (vUpper - vLower) / vMiddle * 100;
} 

[rsy]

Right!

Thats what I want please.... plotted as a non-price-study!

RSy

[eSignal_JasonK]

Hello RSy and xygeek,

Ok, here we go. This formula, BollingerEMAbandwidth.efs, will give you the 20 period bandwidth according to the xygeek's calculation and a 10 period EMA of the bandwidth by default. All the inputs for the Bollinger Study are configurable through "Edit Studies" as well as the length for the EMA.

By the way xygeek, there is an example formula that demonstrates how to code an EMA in our EFS Library. You'll see the same process in this formula with a couple minor modifications.

[rsy]

Thank you very much!

RSy

[xygeek]

Thanks Jason,

I've been wanting an EMA template that can handle custom variables.