BS"D
Ann,
I see you are doing your homework! Actually, there are a few different sets of formulae. For example, some traders like to factor in the day's Open to adjust for opening gaps, etc.
If you go back and read some of my earlier posts you will be amazed at how frequently the Pivot Point projections are spot-on accurate, defining the day's Price Action, starts, stops, turns, and pauses. In fact, when I first started posting Pivot Point charts some folks said it was like magic. The name stuck, thus, Pivot Magic Trading!
Asher
=] ;-)>
http://www.TradingThingys.com