Comments on "New Results on the Characterization of Strictly Positive Real Matrix Transfer Functions"

In this note, we address an inconsistency in our recent article (Hakimi-Moghaddam and Ferrante, 2021). In particular, we provide an example showing that Lemma III.1 of that article is not correct. We show how the statement of this lemma can be modified in order to resolve this inconsistency. We also describe how this modification impact the other results of the article. Notwithstanding the fact that Lemma III.1 plays a central role in the proof of the main result of (Hakimi-Moghaddam and Ferrante, 2021), we show that such a result is indeed correct as it may be derived by using the modified (and correct) version of the lemma. An illustrative example is provided to support the results.