2 citations · 4 across the 8 of their papers we have counts for
5 papers · 2 filters
Numerical ranges of companion matrices: flat portions on the boundary
Jeffrey Eldred, Leiba Rodman, Ilya M. Spitkovsky
Criterion for a companion matrix to have a certain number of flat portions on the boundary of its numerical range is given. The criterion is specialized to the cases of 3-by-3 and…
On singular integral operators with semi-almost periodic coefficients on variable Lebesgue spaces
Alexei Yu. Karlovich, Ilya M. Spitkovsky
Let be a semi-almost periodic matrix function with the almost periodic representatives and at and , respectively. Suppose $p:\mathbb{R}\to(1,\inf…
The possible shapes of numerical ranges
J. William Helton, Ilya M. Spitkovsky
Which convex subsets of the complex plane are the numerical range W(A of some matrix A? This paper gives a precise characterization of these sets. In addition to this we show that…
Factorization, Riemann-Hilbert problems and the corona problem
M. C. Camara, C. Diogo, Yu. I. Karlovich +1
The solvability of the Riemann-Hilbert boundary value problem on the real line is described in the case when its matrix coefficient admits a Wiener-Hopf type factorization with bou…
Non-denseness of factorable matrix functions
Alex Brudnyi, Leiba Rodman, Ilya M. Spitkovsky
It is proved that for certain algebras of continuous functions on compact abelian groups, the set of factorable matrix functions with entries in the algebra is not dense in the gro…