It is necessary to welcome the publication of the paper by Park and Bongiorno Jr (Park, K. and Bongiorno Jr, J.J. (200911.
Park , K and
Bongiorno Jr , JJ . 2009. Persistent Inputs and the Standard H2-multivariable Control Problem. International Journal of Control, 82: 2002–2012. [Taylor & Francis Online], [Web of Science ®]View all references), ‘Persistent Inputs and the Standard
... [Show full abstract] H2-multivariable Control Problem’, International Journal of Control, 82, 2002–2012) in which the special cases in H2-optimisation problems are considered. However, for correct orientation of readers we would like to note some publications which, in our opinion, are connected to a problem given by Park and Bongiorno Jr (200911.
Park , K and
Bongiorno Jr , JJ . 2009. Persistent Inputs and the Standard H2-multivariable Control Problem. International Journal of Control, 82: 2002–2012. [Taylor & Francis Online], [Web of Science ®]View all references), but are absent there.