“…In this context and with focus on particular classes, many schemes have been proposed to tackle the problem. Some are based on a newly elaborated condition of optimality see e.g., [1], [2], [3], others are more related to semi-classical approaches see e.g., [4], [5], [6], [7]. In the last years, there has been a revival of gradient based methods see e.g., [8], [9], [10], [11], [12].…”