3 papers
math.FA2010
Numerical ranges of contractions
Chafiq Benhida, Pamela Gorkin, Dan Timotin
A conjecture of Halmos proved by Choi and Li states that the closure of the numerical range of a contraction on a Hilbert space is the intersection of the closure of the numerical…
math.CV2010
Approximation by polynomials and Blaschke products having all zeros on a circle
David W. Farmer, Pamela Gorkin
We show that a nonvanishing analytic function on a domain in the unit disc can be approximated by (a scalar multiple of) a Blaschke product whose zeros lie on a prescribed circle e…
math.CA2002
The Dirichlet Problem on Quadratic Surfaces
Sheldon Axler, Pamela Gorkin, Karl Voss
We give a fast, exact algorithm for solving Dirichlet problems with polynomial boundary functions on quadratic surfaces in R^n such as ellipsoids, elliptic cylinders, and paraboloi…