“…It has been shown that the BFGS method is very efficient for solving unconstrained optimization problems (1.1) [11,14,47]. For convex minimization problems, the BFGS method are global convergence if the exact line search or some special inexact line search is used [1,2,4,12,16,32,33,38] and its local convergence has been well established [9,10,17]. For general function f, Dai [5] have constructed an example to show that the standard BFGS method may fail for non-convex functions with inexact line search, Mascarenhas [29] showed that the nonconvergence of the standard BFGS method even with exact line search.…”