Counting cells with multiple complex criteria

[macropod]

Originally Posted by TishyMouse

the bit I don't really get (and which isn't explained there) is your multiplication of functions applied to two arrays before sumproduct-ing them with the third array. What does the multiplication do in this instance?

i.e. sumproduct(fx(array1)*fx(array2),fx(array3))

Basically, each array will return a series of true & false results that could be expressed as 1s (true) and 0s (false).
Suppose the first array returns:
1 0 1 0 1 0 1 0
and the second array returns:
0 0 0 1 1 0 1 1
If you multiply the corresponding values from the two array, to find which values are true in both, you end up with:
0 0 0 0 1 0 1 0
(i.e. two true pairs). The SUMPRODUCT simply sums the 1s.