Lindner, MarkoMarkoLindner2019-07-262019-07-262018Opuscula Mathematica 6 (38): 849-857 (2018)http://hdl.handle.net/11420/3028In their recent paper “The spectral norm of a Horadam circulant matrix”, Merikoski, Haukkanen, Mattila and Tossavainen study under which conditions the spectral norm of a general real circulant matrix C equals the modulus of its row/column sum. We improve on their sufficient condition until we have a necessary one. Our results connect the above problem to positivity of sufficiently high powers of the matrix C>C. We then generalize the result to complex circulant matrices.en0860-272720186849857AGH Univ. of Science and Technology PressMathematikJournal Article10.7494/OpMath.2018.38.6.849Other