code: def vel_disp(self, kwargs_profile, kwargs_aperture, kwargs_light, kwargs_anisotropy, num=1000):
          
          sigma_s2_sum = 0
          for i in range(0, num):
              sigma_s2_draw = self._vel_disp_one(kwargs_profile, kwargs_aperture, kwargs_light, kwargs_anisotropy)
              sigma_s2_sum += sigma_s2_draw
          sigma_s2_average = sigma_s2_sum/num
          return np.sqrt(sigma_s2_average)
docs: computes the averaged LOS velocity dispersion in the slit (convolved)
          :param gamma:
          :param phi_E:
          :param r_eff:
          :param r_ani:
          :param R_slit:
          :param FWHM:
          :return: