inverse of polynomial matrix
[Ns,d]=coffg(Fs)
:Fs square polynomial matrix :
coffg computes Fs^-1 where Fs is a polynomial matrix by co- factors method.
Fs inverse = Ns/d
d = common denominator; Ns = numerator (a polynomial matrix)
(For large matrices,be patient...results are generally reliable)
s=`poly`_(0,'s')
a=[ s, s^2+1; s s^2-1];
[a1,d]=coffg(a);
(a1/d)-`inv`_(a)