Unconstrained problem

All the previous results are, almost in theory, sufficient to solve the problem 4.2. The theory of the convex function ensures the existence of a global minimum, while lemma 4.10, corollary 4.10.1, and theorem 4.16 suggest a method to find this minimum. We will see in §5.1 how these methods apply to real circuits, in which, for example, the functions derivative are not available.