Introduction - If you have any usage issues, please Google them yourself
Function: BFGS algorithm for unconstrained problem: min f (x) Input: X0 is the initial point, fun, gfun each objective function and its gradient varargin variable parameter is the input variable, it can be ignored when a simple call bfgs , but other programs will play an important role when the cycle is called output: x, val are approximate optimum and the optimal value, k is the number of iterations.