On Two-Sided Interpolation for Upper Triangular Matrices
The space of upper triangular matrices with Hilbert-Schmidt norm can be viewed as a finite dimensional analogue of the Hardy space H2 of the unit disk when one introduces the adequate notion of "point" evaluation. A bitangential interpolation problem in this setting is studied. The description of all solution in terms of Beurling-Lax representation is given.
D. Alpay and V. Bolotnikov. On two-sided interpolation for upper triangular matrices. Electronic Journal of Linear Algebra (ELA), vol. 6 (1999/2000) pp 31-55.
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