The numerical index of ℓp2


We show that the numerical index of the real (Formula presented.) (Formula presented.) is (Formula presented.) for (Formula presented.) where (Formula presented.) is the root of (Formula presented.) and (Formula presented.). Since (Formula presented.), this improves the main result given by Merí and Quero [On the numerical index of absolute symmetric norms on the plane. Linear Multilinear Algebra. 2020;69:1–9].

Publication Title

Linear and Multilinear Algebra