Subdifferential set of the joint numerical radius of a tuple of matrices
Priyanka Grover, Sushil Singla · Linear and Multilinear Algebra · 2022
An expression for the subdifferential set of the joint numerical radius of a tuple of matrices is obtained. Its applications to the Birkhoff-James orthogonality in the space consisting of tuples of matrices equipped with the joint numerical radius norm are discussed.