Term for when using a single number is used instead of a function? A cost per unit could be 20, but it could also be 20 + 2q (in the cast of the latter, the cost per unit is a function whose result increases with each unit produced).
What is the term to describe when a single number is used where we could also expect a function?
I have in mind 'scalar', but I'm not sure if that's the best term.
A cost function can be constant (in $q$), but this term is not particular to economics.