ic_fu_reff fuis specified, the parameterization uses the original definition of the effective radius as specified in Fu (1996); Fu et al. (1998). By default it uses the same definition of the effective radius as the Key et al. (2002), Yang et al. (2000) and Baum et al. (2005 a); Baum et al. (2005b) parameterizations; see discussion of ic_properties.