From the Macsyma manual... Is this related?
USAGE FILE FOR PACKAGE `TRAN_MAT'
TRAN_MAT is a MACSYMA file which implements an algorithm for the
determination of the transfer function matrix (TFM) of a linear
multivariable
time-independent system described by state-space equations. Consult the
reference at the end of this file for a description of the algorithm, and
consult the demo file for some examples.
.... snip.....
REFERENCE
R.J. Perry, H.H. Sun, and W.A. Berger, "Determination of a Transfer
Function Matrix in Multivariable Systems", IEEE Transactions on Automatic
Control, Vol. 33, No. 3, March 1988.