On two-variable rational interpolation

The goal of this contribution is to investigate interpolation of two-variable rational functions. The tool is the two-variable Loewner matrix, which is an extension of its single-variable counterpart. The main property of the Loewner matrix is that its rank encodes the information concerning minimal complexity interpolants. Both polynomial and generalized state-space (descriptor) realizations of interpolants are presented. Examples illustrate how two-variable rational functions can be recovered from appropriate measurements.