Help With ATR

[ketoma21]

I wrote a Yearly ATR working on a monthly chart and it's calculating correctly (Verified on another platform) except the month of Dec there are a weird spike always, what am I doing wrong?

AAPL or GS for example

[ketoma21]

I know it's a tall order but is there a way I can get ATR numbers for Yearly or quarterly, I think the one I modified down there kind of works.

Thank you very much it's really needed to be added part of another program I'm working on