  For a closed-loop control system with a digital channel between the sensor
and the controller, the notion of invariance entropy quantifies the smallest
average rate of information transmission above which a given compact subset of
the state space can be made invariant. In this work, we present for the first
time an algorithm to numerically compute upper bounds of invariance entropy.
With three examples, for which the exact value of the invariance entropy is
known to us or can be estimated by other means, we demonstrate that the upper
bound obtained by our algorithm is of the same order of magnitude as the actual
value. Additionally, our algorithm provides a static coder-controller scheme
corresponding to the obtained data-rate bound.
