“…First we choose the matrix T such that the linear part of (18) is diagonalized. Next let [x 1x2ȳz ] T = T −1 [w 1 w 2 x 3 x 4 ] T , then in the new coordinate (18) becomeṡ x 1 = −ωx 2 ,ẏ = − g/lȳ +ḡ(x,ȳ,z), x 2 = ωx 1 ,ż = g/lz +h(x,ȳ,z), (20) 47th IEEE CDC, Cancun, Mexico, Dec. [9][10][11]2008 TuB16.3…”