syms s
z=(s^4+10*s^2+9)/(s^3+4*s)
c1=maple('convert',z,'confrac',s,'simple');
pretty(c1)
z2=subs(z,s,1/s)
c2=maple('convert',z2,'confrac',s,'simple');
c2s=subs(c2,s,1/s);
pretty(c2s)