2018/03/26 by Lindner, Marko
#15A60 #15B05 #15B48 #FOS: Mathematics #Functional Analysis (math.FA)
paper · doi:10.48550/arxiv.1803.09526
In 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 \bf 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 \bf C^\top C. We then generalize the result to complex circulant matrices.