text: Title: Elder Force Index
  Body: Hi , 
  
  For the EFI , according to your formula here, you get the difference of current close price - prior close price * volume then you do the exponential weighted average for it. I may have the wrong understanding of it but according to investopedia and thinkorswim, the formula is current close price - prior close price * VFI(13)[ a.k.a 13 period ema of the force index]
  
  Investopedia
  ![image](https://user-images.githubusercontent.com/64815604/89695145-8d035c80-d945-11ea-88e5-8e1dc48e01b8.png)
  
  Thinkorswim
  ![image](https://user-images.githubusercontent.com/64815604/89695186-a5737700-d945-11ea-8d3d-c0c07b3ef25b.png)
  
  
  