Just today I discovered that you can do some cool things w/
conditional sums of the form:

sumproduct(--(A1:A1000="West"),--(B1:B1000="Blue"),C1:C1000)

The above might give me sales in the Western region of Blue things
(column c might have the sales figures). This appears to avoid having
to enter arrary formulas (CTRL SHIFT ENTER as well as the likely
different specification for the formula itself) and would seem to be a
lot easier to work with.

What I haven't seen documented other than quick allusions to it is
exactly what the "--" is doing. Since "--" isn't easy to search for
on the web, I thought somebody here might be able to describe or refer
me to a documentation source online that describes what "--" (&
wrapping w/ () ) is doing. Seems to be a shorthand way to indicate
"do an array operation with this".

Thx!,

- TK