function ShowWavenumbers(kr, casename)

    disp('plot the modal wavenumbers!');

    figure;
    plot(real(kr), imag(kr), 'r*');

    title (casename);
    xlabel('Real Wavenumber (1/m)');
    ylabel('Imaginary Wavenumber (1/m)');
    set   (gca, 'FontSize', 16, 'FontName', 'Times New Roman');

end
