The iterated moment method have been improved to analyze arbitrary cross--sectionor arbitrary index distribution dielectric waveguides by transforming them into tworelated graded index distribution slab waveguides. The convergence speed, the finalprecision as well as the influence of zero order equivlent rectangular border choiceare all discussed through the detailed computation of rectangular core, circular co-te, Ti: LiNbO_3 waveguides and side--polished monomode fibers.