I guess what was left out of both my excellent answer and Chip Pearson's
cited page is that if the function is called from the worksheet, then
to return a matrix it needs to be array entered into the appropriate
sized range, just like the built-in functions.

Alan Beban

Tom Ogilvy wrote:
in addition to Alan's excellent answer, you can look at some additional
information on Chip Pearson's page on this topic:

http://www.cpearson.com/excel/returnin.htm
Returning Arrays