Two Sided Interpolation for Matrix Functions With Entries in the Hardy Space
The two-sided Lagrange-Sylvester interpolation problem is solved in the framework of H2 functions. The extra Hilbert-space structure allows us to give self-contained and independent arguments.
D. Alpay and V. Bolotnikov, Two sided interpolation for matrix functions with entries in the Hardy space. In Linear Algebra and its Applications, Vol. 223/224 (1995) 31-56.