We are often in a position where we wish to exclude certain values from an array of results before passing that array to another function.
For example, a common, practical situation is that of finding the minimum value from a range whilst excluding zeroes. This can be done in several ways, for example using an array formula:
=MIN(IF(A1:A10<>0,A1:A10))
or, if we have Excel 2010 or later, using AGGREGATE:
=AGGREGATE(15,6,A1:A10/(A1:A10<>0),1)