  In spectra of many Seyfert galaxies there is a wide emission line of Fe
$K_\alpha$. The line profile with two maxima supposes that the line emerges in
innermost regions of an accretion disk around a black hole, hence, it is
necessary to take into account General Relativity (GR) effects. In order to
determine GR processes which occur in active galactic nuclei (AGN) an inverse
problem of reconstructing the accreting system parameters from the line profile
has to be solved quickly. In this paper we present a numerical approximation of
the emission line Fe $K_\alpha$ with analytical functions. The approximation is
accomplished for a range of the disk radial coordinate $r$ and the angle
$\theta$ between line of sight and perpendicular to the disk and allows one to
decrease computing time by $10^6$ times in certain astrophysical problems
taking into account all GR effects. The approximation results are available in
the Internet at http://www.iki.rssi.ru/people/repin/approx
