des2tf - descriptor to transfer function conversion
Given the linear system in descriptor form i.e. Sl=list('des',A,B,C,D,E), des2tf converts sl into its transfer function representation:
S=C*(s*E-A)^(-1)*B+D
Called with 3 outputs arguments des2tf returns Bfs and Bis two polynomial matrices, and chis polynomial such that:
S=Bfs/chis - Bis
chis is the determinant of (s*E-A) (up to a xcative constant);
s=poly(0,'s'); G=[1/(s+1),s;1+s^2,3*s^3]; Descrip=tf2des(G);Tf1=des2tf(Descrip) Descrip2=tf2des(G,"withD");Tf2=des2tf(Descrip2) [A,B,C,D,E]=Descrip2(2:6);Tf3=C*inv(s*E-A)*B+D