%
%  code12.m -- quadratic roots (djm - 10 oct 01)
%

pert = -0.5:0.02:0.5;

cmap = colormap;  clf;  hold on 

%  find & plot roots

for j = 1:size(pert,2)
  y = roots([1-pert(j) -2 1]);
  col = cmap(j,:);
  plot(real(y(1)),imag(y(1)),'x','color',col)
  plot(real(y(2)),imag(y(2)),'x','color',col)
end

axis square
title('\bf root locus')
xlabel('\bf real part')
ylabel('\bf imag part')