Correction:

With multiple terms, one only need use at least one unary minus per
conditional, as long as the total number of unary minuses is even.

I find it's easier just to use double unary minuses for each conditional
all the time, if only to avoid thinking/explaining.


In article ,
JE McGimpsey wrote:

If you're going to let SUMPRODUCT to the array multiplication by
using the comma notation, the double unary minuses are needed. The
latter is slightly more efficient.