function [rtab,info]=routh(den)
info=[];
vec1=den(1:2:length(den)); nrT=length(vec1);
vec2=den(2:2:length(den)-1);
rtab=[vec1; vec2, zeros(1,nrT-length(vec2))];
for k=1:length(den)-2,
alpha(k)=vec1(1)/vec2(1);
for i=1:length(vec2),
a3(i)=rtab(k,i+1)-alpha(k)*rtab(k+1,i+1);
end
if sum(abs(a3))==0
a3=polyder(vec2);
info=[info,'All elements in row ',...
int2str(k+2) ' are zeros;'];
elseif abs(a3(1))<eps
a3(1)=1e-6;
info=[info,'Replaced first element;'];
end
rtab=[rtab; a3, zeros(1,nrT-length(a3))];
vec1=vec2; vec2=a3;
end