clear all;
close all;

gamma=0*0.1;
om=pi;

A=[0, 1;-1, -2*gamma];

dt=0.02;

EA=expm(A*dt);

xt=[1,0]';
x0=xt;
Nt=1000;
X=zeros(2,Nt);
t=zeros(1,Nt);

for it=1:Nt;
    t(it)=it*dt;
    
    A=[0, 1; -1+0.1*cos(om*t(it)), -2*gamma];
    EA=expm(A*dt); 
    xt=EA*xt;
    %xt1=expm(A*t(it))*x0;
    %e(it)=norm(xt-xt1);
     X(:,it)=xt;
   
    figure(1);
    plot(xt(1),xt(2),'.r');
    axis([-1.2,1.2,-1.2,1.2])
    axis square
    drawnow;
    hold on
   
end;


hold off

figure(2)
plot(t,X(1,:),'r',t,X(2,:),'b',t,0*t,'k','linewidth',2)
xlabel('t');ylabel('x(t)')
drawnow;