Branch and bound computation of the minimum norm of a linear fractional transformation over a structured set

The minimum norm of a linear fractional transformation (LFT) over a structu red set is computed using a branch and bound algorithm. This is a global op timization problem caused by the possibility of local minima. Several compu tationally efficient lower bounds for the minimum norm of the LFT are devel oped, and it is demonstrated that the success of the optimization, as measu red by time-to-converge, largely depends on the quality of these bounds.