  The Jacobi and Weierstrass elliptic functions used to be part of the standard
mathematical arsenal of physics students. They appear as solutions of many
important problems in classical mechanics: the motion of a planar pendulum
(Jacobi), the motion of a force-free asymmetric top (Jacobi), the motion of a
spherical pendulum (Weierstrass), and the motion of a heavy symmetric top with
one fixed point (Weierstrass). The problem of the planar pendulum, in fact, can
be used to construct the general connection between the Jacobi and Weierstrass
elliptic functions. The easy access to mathematical software by physics
students suggests that they might reappear as useful tools in the undergraduate
curriculum.
