clear
clf

m = 1;
G = 1e-6;
M = 3e+6;

% initial positions
r = ...

% initial velocities
v = ...

tMax = 10.0;

%choose a time step
dt = ...

xt = r(1);
yt = r(2);

while (t<tMax) 
    % now enter the vector for the change in position during step 'dt'
    dr = ...
    
    % (1) derive the force vector 'F'
    % (2) from that the acceleration vector 'a'
    % (3) from that the difference in velocity 'dv'
    dv = ...
    
    % now update the position and velocity
    ...
    ...
    t = t +dt;
    
    % we want to keep the trajectory for plotting below
    xt = [xt , r(1)];
    yt = [yt , r(2)];    
end

plot(0,0,'x',xt,yt,'r--');
axis equal