On Monday 22 Sep 2003 2:36 pm, I wrote:
The 'infinite loop' is due to the speed of the pbeta routine, rather than the initial approximation from the qbeta. There is another algorithm available for pbeta (Algorithm 708, CACM 18. 360--373, 1992)
That should be TOMS, not CACM. Sorry.
which may be of use here. This continued fraction approximation is recommended by Numerical Recipes over the power series approximation (make of that what you will!)
TimM.