Could someone point me in the right direction with a formula. I am trying to
use excel to backtest some trading rules and one column designates a long or
short position and the next column designates the entry price. I am trying
to create a third column that will add up the difference between the short
and and long entries. Assuming that there is a position either long or short
all of the time.

For example:
A1 = 1, B1 = 44.00
A2 = 1,
A3 = 1.
A4 = -1, B4 = 47.00
A5 = -1,
A6 = -1,
A7 = 1, B7 = 48.00....

Is there a way to write a formula that will sum up the difference between
the long and short positions?

Regards,

Dismal