90+2) 9+Dq0 9+1) 90 Φ(g*)）=0 Graphic representation Root at inflection point Desired solution q0+1)g0 90 Multiple roots Divergence near a minimum or maximumq(j+1) q(j)  (q* )=0 Graphic representation q(j) q(j+1) q(j+2) Root at inflection point q(j) q(j+1) Multiple roots Desired solution q(j) Divergence near a minimum or maximum