from gms: What would be a way to calculate what today's price would have to be to make the 10-day and 15-day simple moving averages cross today?
I started to provide an answer, but there were some difficulties.
Let's break it down:
(1) You are looking for a x-over of 10d-15d.
(2) You need either the 10d or the 15d to move enough to make that cross over.
(3) Most x-overs take a position on the short MA crossing the long MA
(4) Therefore, the Q is what
price TODAY would make the 10d ma = 15d ma TODAY
Mind you, this must pre-suppose that the 15d MA is moving in the direction you want to trade.
OK, having said all that, here's the calculation:
(1) 10d MA = 10d=(d1+d2+d3+d4+d5+d6+d7+d8+d9+d10)/10, where d1 through d10 are prices from 10 days ago, starting yesterday
(2) 10d MA = a (known)
(3) 15d MA = b (known)
(4) 10d MA(x-over) = b (ie, = 15ma) = (d2+d3+d4+d5+d6+d7+d8+d9+d10+d11)/10, where d11 is TODAY'S DESIRED PRICE.
To get todays desired price (d11), notice we dropped d1 and added in the yet unknown d11. You know the last 9 days prices.
You need to solve for d11 (The PRICE TODAY to make 10d=15d):
d11 = [(15d MA) times 10 ] / (d2+d3+d4+d5+d6+d7+d8+d9+d10)
Sorry if it sounds simpleton (or too complex, lol)... amg