x0=[1.2; 0; 0; -1.04935751];
tic, [t,y]=ode45(@apolloeq,[0,20],x0); toc
length(t), plot(y(:,1),y(:,3))
 
options=odeset; options.RelTol=1e-6;
tic, [t1,y1]=ode45(@apolloeq,[0,20],x0,options); toc
length(t1), plot(y1(:,1),y1(:,3)),

plot(t(1:end-1),diff(t))