A couple of questions about Bessel functions:
(1) Shouldn't this return return a symbolic expression, so that it can be used as part of an expression to be evaluated later with a specific r:
sage: var('r') sage: bessel_J(0,r)
I'm thinking specifically of building up a series that will later be plotted.
(2) There was talk a while back about making the zeros of the Bessel functions available without having to calculate them with find_root() (Not that there's a problem doing that, but it would just be a convenience.)