Need a customized ATR function in MQL4 (math oriented coder only)

Hi,

I need a small MQL4 function that will take the "shift" of a bar as parameter and a customized version of ATR taken from a formula which I will provide in discussion area.

Basically I just want to take the original ATR source code and customize it a little bit and converted into a function that I can use in my own source code.

An example usage would be:  

double CustomATR = GetMyCustomATR(int shift, double& SecParam) ;

{

 .... 

} 

void Start

{ 

double OtherParam = 0;

double MyATR = GetMyCustomATR(1, OtherParam); 

}