[Top][All Lists]

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
## Re: [Bug-gsl] Re: hyperg_U(a, b, x) Questions about x<0 and values of a

**From**: |
Brian Gough |

**Subject**: |
Re: [Bug-gsl] Re: hyperg_U(a, b, x) Questions about x<0 and values of a, |

**Date**: |
Wed, 21 Jul 2010 21:24:01 +0100 |

**User-agent**: |
Wanderlust/2.15.6 (Almost Unreal) Emacs/23.2 Mule/6.0 (HANACHIRUSATO) |

At Sun, 11 Jul 2010 14:43:43 -0500,
Raymond Rogers wrote:
>* *
>* hyperg_U basically fails with b=1, a non-integer; because*
>* gsl_sf_poch_e(1+a-b,-a,&r1); is throwing a domain error when given*
>* gamma(0)/gamma(a).*
>* Checking on and using b=1 after a-integer is checked is illustrated*
>* below in Octave. I also put in recursion to evaluate b>=2.*
>* I checked the b=1 expression against Maple; for a few values x<0,a<0,b=1*
>* and x<0,a<0,b>=2 integer.*
>* --------------*
>* Unfortunately the routine in Octave to call hyperg_U is only set up for*
>* real returns, which was okay for versions <1.14 . Sad to say I am the*
>* one who implemented the hyperg_U interface, and will probably have to go*
>* back :-( . Integrating these functions into Octave was not pleasant;*
>* but perhaps somebody made it easier. I did translate the active parts*
>* of hyperg_U into octave though; so it can be used in that way.*
Thanks for the comments, I've logged them for future review in the bug tracker
at
https://savannah.gnu.org/bugs/index.php?30510
It's a complicated function so it's going to take some time to digest it.