for N=2:100

    D1=DM1(N); D2=D1*D1; 

    for i=1:N-1
        for j=1:N-1
          A(i,j)=D2(i+1,j+1);
        end
    end

    aa=max(abs(eig(A)));
    cc=min(abs(eig(A)));
    bb=aa/cc;

    xx(N-1)=N;
    err(N-1)=aa/(N^4);
    frr(N-1)=bb/(N^4);
    grr(N-1)=cc;

end

    fprintf(1,      '%16.0f          %13.3e  \n', [xx;  frr]);

    semilogy (xx, frr)