The companion matrix of a monic linear differential operator Dn + an - 1Dn - 1 + ... + a0 ∈F[D] is defined as the n x n matrix
Returns the companion matrix of the monic differential operator L.
> F<z> := RationalDifferentialField(Rationals()); > R<D> := DifferentialOperatorRing(F); > L := D^3-z*D^2+2*D+5; > CompanionMatrix(L); [0 1 0] [0 0 1] [-5 -2 z]