eplogpar: log-parabolic blazar model with $\nu$F$_{\nu }$ normalization

eplogpar is a power-law with an index which varies with energy as a log parabola.

$$A(E) = 10^{-\beta(\log(E/E_p))^2} / E^2$$

par1	$E_p$, the peak energy in $\nu$F$_{\nu }$
par2	$\beta$, curvature term
norm	K, the flux in $\nu$F$_{\nu }$ units at energy $E_p$ keV

See for instance Tramacere et al. (2007) and Tramacere et al. (2009).