code: def _particle_func(self, coords, pos, wid):
          
          dx, dy, dz = [c - p for c,p in zip(coords, pos)]
          dr2 = dx*dx + dy*dy + dz*dz
          return np.exp(-dr2/(2*wid*wid))
docs: Draws a gaussian, range is (0,1]. Coords = [3,n]