def vel_disp(self, kwargs_profile, kwargs_aperture, kwargs_light, kwargs_anisotropy, num=1000):
        """
        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:
        """
        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)