$\dot{x}=v_x$
$\dot{y}=v_y$
$\dot{v_x}=\frac{Cx}{(x^2+y^2)^{3/2}}$
$\dot{v_y}=\frac{Cy}{(x^2+y^2)^{3/2}}$
where $C$ is a constant.
How is this solvable (assuming initial conditions are given)?
If I want to use something like
[t,y] = ode23(@f,tspan,initial_condition)
then what should my $f$ be?