gravity_force_func.m

%% Returns the force gravity on m1 due to m2.
function res = gravity_force_func(point1, m1, point2, m2)
    % Returns force exherted by m1 on m2
    res = force(point2, point1);

    %% Returns force of gravity directed in direction from from to to.
    function res = force(from, to)
       G = 6.67 * 1e-11; % N m^2 / kg^2
       R = to - from; % how far from "from" is "to"? This is the vector to it
       mag_r = norm(R); % magnitude of the direction vector
       dir_r = (R) / mag_r; % unit vector in direction from to to.
       Fg = G * m1 * m2 / mag_r^2; % magnitude of force of gravity
       res = Fg * dir_r; % force of gravity in direction from from to to
    end

end