@Article{Aretaki2011,
author = "Aretaki, Aikaterini and Maroulas, John",
title = "Investigating the numerical range and q-numerical range of non square matrices",
journal = "Opuscula Math.",
year = "2011",
volume = "31",
number = "3",
pages = "303--315",
doi = "http://dx.doi.org/10.7494/OpMath.2011.31.3.303",
url = "http://dx.doi.org/10.7494/OpMath.2011.31.3.303",
abstract = "A presentation of numerical ranges for rectangular matrices is undertaken in this paper, introducing two different definitions and elaborating basic properties. Further, we extend to the \(q\)-numerical range.",
keywords = "numerical range, projectors, matrix norms, singular values",
issn = "1232-9274"
}