    function y=lcond(l)
    [n,n]=size(l); y=zeros(n,1);
    for i=1:n, p(i)=0; end
    for k=1:n
      y(k)=(-sig(p(k))-p(k))/l(k,k);
      for i=n:-1:k+1
        p(i)=p(i)+l(i,k)*y(k);
      end
    end

