Outdated Archival Version

These pages are not updated anymore. They reflect the state of 2 Oct 2005. For the current production of this journal, please refer to http://www.tandfonline.com/loi/uexm20.

Some remarks on real and complex output feedback

We provide some new necessary and sufficient conditions which guarantee arbitrary pole placement of a particular linear system over the complex numbers. We also exhibit a non-trivial real linear system which is not controllable by real static output feedback and discuss a conjecture from algebraic geometry concerning the existence of real linear systems for which all static feedback laws are real.

For an amplification of our example of a non-trivial real linear system which is not controllable with real output feedback, a further discussion of computational issues, and the MAPLE/SINGULAR scripts we used, click here.