... This formula is a function of the morphological type, t , and of the apparent flattening, logr25 . ... R is the axis ratio derived from logr25 . k is the bulge to disk ratio and depends on morphological type as follows: k=0.754*10 (-0.2*t) , if k >1 then k=1 (Simien and de Vaucouleurs) . ... It depends on the morphological type t as: . ... K = 0.094 if t >= 0. and C is defined as (dlogD/dlogR) and has the fixed value of 0.04 . ...