  Initially introduced in the framework of quantum control, the so-called
"monotonic algorithms" have demonstrated excellent numerical performance when
dealing with bilinear optimal control problems. This paper presents a unified
formulation that can be applied to more nonlinear settings compatible with the
hypothesis detailed below. In this framework, we show that the well-posedness
of the general algorithm is related to a nonlinear evolution equation. We prove
the existence of the solution to this equation and give important properties of
the optimal control functional. Finally we show how the algorithm works for
selected models from the literature and compare it with the gradient algorithm.
