transfer to controllable state-space
[sl]=cont_frm(NUM,den)
:NUM polynomial matrix : :den polynomial : :sl syslin list, sl=[A,B,C,D]. :
controllable state-space form of the transfer NUM/den.
s=`poly`_(0,'s');NUM=[1+s,s];den=s^2-5*s+1;
sl=cont_frm(NUM,den);
slss=`ss2tf`_(sl); //Compare with NUM/den