I've only used excel a few times, and what I've read so far doesn't
tell me if this is possible, tho' I have to assume it is. Is it
possible to
assign a formula to a column, say, and have the entire column be
set to a formula with the values of other columns on a row-by-row
basis? That is, something like Cx=Ax+Bx. And since I want it to
be able to handle odd situations, like the absence of some entries,
to set tests -- like set a variable to some value if the cell has no
entry, or has, say, a letter instead of a number? The sort of thing
I could do in APL? Would this require some sort of additional package
to install in Excel? Or does excel do this by itself?

Thanks!

Mark