I think perhaps he s using it as a worksheet function  in each of four
cells, like



A B C D

1

2 =MainFunc(H2:H5)

3 =MainFunc(H2:H5)

4 =MainFunc(H2:H5)

5 =MainFunc(H2:H5)

6



I think he's trying to learn how to return an array  of values from a
function into a Range in some way. I'm not sure how to do this myself...