  This is a complete version of the 6-page IEEE TAC technical note [1]. In this
paper, we consider the distributed surrounding of a convex target set by a
group of agents with switching communication graphs. We propose a distributed
controller to surround a given set with the same distance and desired
projection angles specified by a complex-value adjacency matrix. Under mild
connectivity assumptions, we give results in both consistent and inconsistent
cases for the set surrounding in a plane. Also, we provide sufficient
conditions for the multi-agent coordination when the convex set contains only
the origin.
