Yang, Y.Tits, A.L.Qiu, L.Recently, Qiu et al. obtained a computationally attractive formula for the computation of the real stability radius. This formula involves a global maximization over frequency. Here we show that the frequency range can be limited to a certain finite interval. Numerical experimentation suggests that this interval is often reasonably small.en-USrobust controlstabilityIntelligent ServomechanismsTechnical Report