The Nevanlinna-Schur algorithm with real coefficients

Shows that the Nevanlinna-Schur (NS) algorithm, in the case of scalar interpolation problems, allows for real arithmetic by a suitable combination of steps corresponding to complex conjugate interpolation data. It is noted that this property does not hold in general in the case of matricial interpolation. Further, it is pointed out that the resulting formulae are identical, modulo a scalar factor, to those in an analogous algorithm in Youla-Hazony positive real cascade synthesis