@staticmethod
def rho(rhos, x):
    """
		The NFW density as a function of :math:`x = r/r_{\\rm s}`.
		
		This routine can be called without instantiating an NFWProfile object. In most cases, the 
		:func:`~halo.profile_base.HaloDensityProfile.density` function should be used instead.

		Parameters
		-------------------------------------------------------------------------------------------
		rhos: float
			The central density in physical :math:`M_{\\odot} h^2 / {\\rm kpc}^3`.
		x: array_like
			The radius in units of the scale radius, :math:`x=r/r_{\\rm s}`; can be a number or a 
			numpy array.
		
		Returns
		-------------------------------------------------------------------------------------------
		rho: array_like
			Density in physical :math:`M_{\\odot} h^2 / {\\rm kpc}^3`; has the same dimensions 
			as ``x``.

		See also
		-------------------------------------------------------------------------------------------
		halo.profile_base.HaloDensityProfile.density: Density as a function of radius.
		"""
    return rhos / x / (1.0 + x) ** 2
