Interesting analogy, I guess it may be a "special case" of a matrix product
.... however, whereas matric arithmetic doesn't care if the two arrays (or
vectors) are of the same size, Excel does (at least in this case, so far as
I know). It fails if each array does not have the same number of elements.


"Andrew Chalk" wrote in message
...
OK. A cross-product in matrix parlance?

Thanks for the detail. Same goes for QWilliam and Harlan's replies.

- Andrew
"Chip Pearson" wrote in message
...
It serves as an "AND" condition. In the formula,

(A2:A500="5/27/2005")
and
(E2:E500="5098")

return arrays of TRUE or FALSE values, each indicating the result
of the comparison. So, for example, you'll get two arrays like

{TRUE, TRUE, FALSE, .....} and {FALSE, TRUE, TRUE, ....}

The multiplication operator * multiplies these two arrays
together; each element in the first array is multiplied by the
corresponding element in the second array, and the result is an
array of these products.

Since Excel treats TRUE as 1 and FALSE as 0, the resulting
product of the multiplication will be 1 (or TRUE) only when both
operands are TRUE (or 1).

So, using the example arrays above, the result of the
multiplication is

(0, 1, 0, ...)


--
Cordially,
Chip Pearson
Microsoft MVP - Excel
Pearson Software Consulting, LLC
www.cpearson.com




"Andrew Chalk" wrote in
message ...
In the formula below, what does the asterisk '*' mean?

=COUNT(IF((A2:A500="5/27/2005")*(E2:E500="5098"),E2:E500))


Many thanks