I have a question relating to non-linear optimization and hope to receive your help! If i have a cost function F(x) in general form. I mean it can not be described in the form of F(x)= f(x)'.f(x) (where f(x)' is transposition of f(x) ) as required by some methods such as Levenberg-Marquardt, Gauss-Newton for finding a local minimum value. If i want to use above two methods, what should i do ? Do you know any method that i can use in this case?