i am confused as to when to use "=" and when "==" is correct. My most recent model has been that "=" means "is defined as", while "==" means "evaluates to the same as".
But that does not make sense either, since for example stuff like
plot(f.subs(a == 3), (x, -1, +1)) is clearly a definition, not an evaluation.
So please someone explain this to me.
