"Variable" in math doesn't mean change, it means that the relation a variable is involved in holds over any variation of valid denotations of that variable. So

"Variable" in math doesn't mean change, it means that the relation a variable is involved in holds over any variation of valid denotations of that variable. So the notion of variance is external to the proposition, whereas in programming the variation is internalized. (Technically we ought to talk about variables assigned in "for all" style or "there exists" style bindings. There's still a sense of holding under all variations, but the "thing" that "holds" changes.) On the other hand, constant is different in each domain. Pi, the constant, is emphatically not a variable in mathematics.