aminit;

a = 0.6;
sys = tf([1], [1 3*a 3*a*a a^3]);

figure(1); clf; xsubplot(221);
axis([-2 6 -4 4]); daspect(daspect);		% set up axes w/ right limits

amnyquist(sys, logspace(-3, 3, 1000));
% axis([-3 5 -4 4]); daspect(daspect);

% Add axis labels
hold on; plot([-1 1 2 3 4 5], [0 0 0 0 0 0], 'k+', ...
  'LineWidth', AM_tick_linewidth);
amtext([-1-0.5 1 3 5] - 0.1, [0 0 0 0] - 0.65, {'-1', '1', '3', '5'});

hold on; plot([0 0], [-2 2], 'k+', 'LineWidth', AM_tick_linewidth);
amtext([0 0] + 0.3, [-2 2], {'-2', '2'});

amprint('nyquist-threepole.eps');
