horner - polynomial/rational evaluation
evaluates the polynomial or rational matrix P = P(s) when the variable s of the polynomial is replaced by x :
horner(P,x) = P(x)
Example (Bilinear transform): Assume P = P(s) is a rational matrix then the rational matrix P((1+s)/(1-s)) is obtained by horner(P,(1+s)/(1-s)) .
To evaluate a rational matrix at given frequencies use preferably the freq primitive.
s=poly(0,'s');M=[s,1/s]; horner(M,1) horner(M,%i) horner(M,1/s)