def net_forces(self):
""" produces a matrix of force components for all bodies """
self._f_matrix.fill(0)
count = 0
for body in self._body_list:
for body2 in self._body_list:
if body != body2:
net_force = Physics.gravitational_force(
body.get_mass(), body2.get_mass(),
self.euclidean_distance(body.get_position(),
body2.get_position()),
self.get_dist_change(body.get_position(),
body2.get_position()))
self._f_matrix[:, count] += net_force
count += 1
self._analytics.add_data(self._t, la.norm(self._f_matrix[:, 1]))
