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).