@XanderHenderson Perhaps you are thinking about math.stackexchange.com/questions/3286355/… ?

The above link is to Scalar-valued function definition. (Just including the title for better readability.)

This is probably only marginally related: Why do we use the word “scalar” and not “number” in Linear Algebra?

@AloizioMacedo Yes! Thank you. I need to get better with the built-in search functionality---I was not finding anything, but was using Google. :\