Any Pivot Point Formulas?

Hey guys, I use to trade in forex and I've been developing my own pivot points indicator. The software which I use doesn't have the feature built-in and I like to calculate weekly pivots.

how should I handle non-trading days in a week (e.g. public holidays) - say a week has 1 non-trading day, so now is the pivot calc based on 4 days or does it stick with a 5 day lookback (i.e. assume every 5 daily bars make up a week). If there are 2 holidays in one week is the pivot then based on 3 days and so on?