Fast Calculation of Gravitational Lensing Properties of Elliptical
  Navarro-Frenk-White and Hernquist Density Profiles
  We present a new approach for fast calculation of gravitational lensing
properties, including the lens potential, deflection angles, convergence, and
shear, of elliptical Navarro-Frenk-White (NFW) and Hernquist density profiles,
by approximating them by superpositions of elliptical density profiles for
which simple analytic expressions of gravitational lensing properties are
available. This model achieves high fractional accuracy better than $10^{-4}$
in the range of the radius normalized by the scale radius of $10^{-4}-10^3$.
These new approximations are $\sim 300$ times faster in solving the lens
equation for a point source compared with the traditional approach resorting to
expensive numerical integrations, and are implemented in {\tt glafic} software.
