(17)

can be expressed, when normalized by the factor √(z1 − z3)/2, by the inverse elliptic function in the form

mt = ∫ zz3 √ (z1 − z3) dz
√ [4 (z1 − z) (z2 − z) (z − z3)]
= sn−1 √ z − z3= cn−1 √ z2 − z= dn−1 √ z1 − z.
z2 − z3 z2 − z3z1 − z3

(18)

z − z3 = (z2 − z3) sn2mt, z2 − z = (z2 − z3) cn2mt, z1 − z = (z1 − z3) dn2mt.

(19)

z = z2sn2mt + z3cn2mt.

(20)

Interpreted dynamically, the axis of the top keeps time with the beats of a simple pendulum of length