2. I don't understand what you mean by "a method for non-linear transformation". Do you mean converting, say, y= f(x) to Y= F(X)? If so, no there is no general simple formula. It depends basically on finding inverses for the two transformation functions. If g and h have inverses (which is not necessarily true for non-linear functions) then y= f(x) would be $h^{-1}(Y)= f(g^{-1}(X)$ so that $Y= h(f(g^{-1}(X)))$.