16 citations · 96 across the 45 of their papers we have counts for
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On the Crouzeix ratio for matrices
Bartosz Malman, Javad Mashreghi, Ryan O'Loughlin +1
The Crouzeix ratio of an complex matrix is the supremum of taken over all polynomials such that on the numerical range of . It i…
Double-layer potentials, configuration constants and applications to numerical ranges
Bartosz Malman, Javad Mashreghi, Ryan O'Loughlin +1
Given a compact convex planar domain with non-empty interior, the classical Neumann's configuration constant is the norm of the Neumann-Poincaré operator $K…
Asymptotically equicontinuous sequences of operators and a Banach-Steinhaus type theorem
Javad Mashreghi, Thomas Ransford
We introduce the notion of an asymptotically equicontinuous sequence of linear operators, and use it to prove the following result. If are topological vector spaces, if $T_n,…
Summability and duality
Soumitra Ghara, Javad Mashreghi, Thomas Ransford
We formalize the observation that the same summability methods converge in a Banach space and its dual . At the same time we determine conditions under which these methods…
Norms of polynomials of the Volterra operator
Thomas Ransford, Nathan Walsh
We compute the operator norm of real-quadratic polynomials of the Volterra operator. This is used to test whether the Crouzeix conjecture holds for the Volterra operator.
A four-mean theorem and its application to pseudospectra
Thomas Ransford, Nathan Walsh
Let . We show that, if and are -tuples of strictly positive numbers whose arithmetic, geometric and harmonic means agree, then \[ \max_j…