SHARE2;BFFAC BFZETA contains cheap and dirty BFLOAT versions of the
Factorial (shifted Gamma) and Riemann Zeta functions.  Both BFFAC
and BFZETA take a 2nd argument which is how many digits to retain and
return, but it's a good idea to request a couple of extra.

BFPSI(n,z,fpprec) gives polygammas of real arg and integer order.
For digamma, BFPSI0(z,fpprec) is more direct.  Note -BFPSI0(1,fpprec)
provides BFLOATed %GAMMA.

There is also CBFAC(z,fpprec) for factorial of complex z, which is
even slower!

BURN(n) is a way to get isolated bernoulli numbers faster than BERN(n)
when n > 105 or so.

There is also the Hurwitz zeta fcn BHZETA(s,h,fpprec), which gives
fpprec digits of sum((k+h)^-s,k,0,inf). --RWG