F distribution on the 41C

[Dieter]

(12-17-2015 07:37 PM)Dieter Wrote:  At the moment the incomplete Beta function uses code from the HP67/97 library, which of course can be optimized. That's why I do not want to post this more or less experimental code now. Just want to say it's not that complicated (about 160 lines now). ;-)

OK, I now got something that seems to work, based on the regularized Beta algorithm of the HP35s statistical distributions pack. Which in turn is a variant of the modified Lentz method suggested in the Numerical Recipes book.

The whole thing consists of about 200 lines of code. The regularized Beta function I_x(a,b) and Euler's Beta B(a,b) (...for integers and half-integers) can be called separately. So if you like you can also set up Student's t and the Binomial distribution quite easily. Compared to the timings given on JMB's website this version runs about 30% faster.

Maybe I should do some tests now...

Dieter