How to plot vectorfield in the phase portrait ..... How to modify the code....

clear

figure

hold on

epsilon=0.01;omega=0.112;theta=0.14;gamma=2.54;

sys = @(t,x) [-x(1)*(x(1)-theta)*(x(1)-1)-x(2)+omega;epsilon*(x(1)-gamma*x(2))];

[t,xs] = ode45(sys,[0 100],[1 .1]);

plot(xs(:,1),xs(:,2));

x=-0.4:0.01:1.2;

plot(x,x./gamma,'r',x,omega-x.*(x-theta).*(x-1),'m')

hold off

axis([-0.4 1.2 0 0.4])

fsize=15;

set(gca,'XTick',-0.4:0.2:1.2,'FontSize',fsize)

set(gca,'YTick',0:0.1:0.4,'FontSize',fsize)

xlabel('u(t)','FontSize',fsize)

ylabel('v(t)','FontSize',fsize)

hold off

How to plot vectorfield in the phase portrait ..... How to modify the code....