I am trying to automatically fill (or series fill) a finite (but variable) length column with a linear series of numbers that start at zero, increase at a constant step rate, and then automatically stop when the filled value equals or exceeds the value of a selected cell containing a number entered by a non-technical user of the worksheet. This column of numbers is then used as the X-values (domain) for an exponential function based on other parameters entered by the user. That part's all figured out.

Any thoughts on how to fill in a column of numbers automatically with out using the Auto Fill pulldown or the Series Fill function?

Those two ways don't appear to solve my problem.

Is there something like a combination of a simple calculation with a programmer's IF function in Excel?
I was tolerably acquainted with Visual Basic some years back, but I've forgotten it all.

I know about 33% of Excel quite well, but the other 67% is a deep, dark mystery.