span = [0 10000];

r0 = 1e7;
v0 = sqrt(4e14/r0);
t0 = 0.0/180*pi;
n0 = sqrt(4e14/r0/r0/r0);
TT0 = 2*pi/n0

state = [ r0*cos(t0) r0*sin(t0) -v0*sin(t0) v0*cos(t0) ];
option = odeset('AbsTol',1e-10);
[t,y] = ODE45('satdyn',span,state,option);
plot(y(:,1),y(:,2))