Can anyone Help

[jsaitch]

I am trying to make simple Indicator based on Elders Force Index, the indicator works fine until I try to add an exponential moving average to it.

I am sur there is a simple error

[jsaitch]

Can someone also help me to get a Centre Line based @ 0


Cheers


and thanks in advance




Jamie

[ACM]

Jamie
The built-in studies require a series as a source. This series can be either a price series, another built-in study or a custom series. To create a custom series you need to use either the efsInternal() or the efsExternal() functions which retrieve the result of a calculation performed in a separate function or external efs and convert it to a series.
For the description of the these functions and the required syntax see the links above which will take you to the corresponding articles in the EFS KnowledgeBase. Further information together with some examples can be found in this thread.
In the case of your efs you need to first create a separate function within that same script and call it (for example) myCalc. In that function you process the equation

myVar = volume(0) * ( close(0) - close(-1)); 

You then use myVar as the return for that function.
Once you have done that you create the series in the main function using efsInternal() and then use that series as the source for the ema study.

var mySeries = efsInternal("myCalc");//this calls the separate function and creates the series
var myAverage = ema(10, mySeries); //built-in study uses the custom series as source 

You could also write it as follows if you do not need the custom series as a separate variable.

var myAverage = ema(10, efsInternal("myCalc")); 

In either case you would use myAverage as the return..
As an example see the Chaikin oscillator study in this thread which has a very similar contruct to the one I just described here.
Alex

[ACM]

Jamie
To add the centerline at 0 use the addBand() function
Alex

[jsaitch]

Thanks very much for your help