% `splane` creates a pole-zero plot using pole and zero inputs with the
% real and imaginary axes superimposed
function splane(z,p)
    x1 = real(z);
    x2 = real(p);
    y1 = imag(z);
    y2 = imag(p);

    plot(x1, y1, 'o', x2, y2, 'x');
    xlabel('Real Part');
    ylabel('Imaginary Part');
    axis('equal');
    line([0 0], ylim(), 'LineStyle', ':');
    line(xlim(), [0 0], 'LineStyle', ':');
end