format long
x=[0.3,0.4,0.5,0.6];
e=[0.5488,0.4493,0.3679,0.3012];
y=e-x;
q=zeros(4);
q(:,1)=x';
z=0;
for i=1:3
  for j=i:3
    q(j+1,i+1)=((z-y(j-i+1))*q(j+1,i)-(z-y(j+1))*q(j,i))/y(j+1)-y(j-i+1);
  end
end
q(4,4)