D. Alpay et al., ON THE TANGENTIAL INTERPOLATION PROBLEM FOR H-2 FUNCTIONS, Transactions of the American Mathematical Society, 347(2), 1995, pp. 675-686
The aim of this paper is to solve a matrix-valued version of the Nevan
linna-Pick interpolation problem for H-2 functions. We reduce this pro
blem to a Nevanlinna-Pick interpolation problem for Schur functions an
d obtain a linear fractional transformation which describes the set of
all solutions.