Spectral Theory, Mathematical System Theory, Evolution Equations, Differential and Difference Equations pp 121-130 | Cite as

# Extension of the *ν*-metric: the *H*^{∞} Case

## Abstract

An abstract *ν*-metric was introduced by Ball and Sasane, with a view towards extending the classical *ν*-metric of Vinnicombe from the case of rational transfer functions to more general nonrational transfer function classes of infinite-dimensional linear control systems.In this short note, we give an additional concrete special instance of the abstract *ν*-metric, by verifying all the assumptions demanded in the abstract set-up.T his example links the abstract *ν*-metric with the one proposed by Vinnicombe as a candidate for the *ν*-metric for nonrational plants.

## Keywords

*ν*-metric robust control Hardy algebra quasianalytic functions

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## References

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