q = 0.18: S_2/S_3 = 0.99573, S_4/S_3 = 0.94685
sign +1: worst relative margin +0.00131 at a1 = 0.5738, a2 = 0.5738
    margin +0.00131  a1 = 0.5738  a2 = 0.5738
sign -1: worst relative margin +0.01264 at a1 = 0.1000, a2 = 0.0200
